Keyboard and trackpad stopped working, it works only in login. Help?

All of these people and no answer i think i figured it out go to your system preferences. You will need to have a working mouse to get there obviously. Once your there go to Accessibility then click on the mouse and trackpad option. Once you are there you will most likely have ignore built in trackpad while using mouse. Uncheck that and your track pad should work now. You can disconnect your mouse and you should be good to go. At least thats what worked for me hope that helps.

Try starting up in Safe Mode by holding down the Shift key on startup. This will disable any extensions that may have been inadvertently installed. If it does start up and run OK, you know it is a software issue. Also try starting up in repair mode by holding down the R key and run Disk Utilities.

For anyone who may still be having this problem, I have just fixed the issue for a MacBook Air I am working on.

I tried all the PRAM resetting, deleting plist files, terminal commands, removing bluetooth devices and checking for viruses of which none of those methods worked.

I then turned to hardware as my issue, I removed the bottom cover and the battery then proceeded to remove the trackpad flex cable.

Once I had removed the flex cable I flipped it over to see the pins on the under side of the cable, I noticed on the motherboard side there was some black dust or debris or something on there so I cleaned that off with some isopropyl and a cotton tip and put it all back together and there you have it! It is all working for me now with no issues.

Creating a new user worked for me! I copied my desktop, documents, and downloads folder, created a new user, and pasted everything there :)

I did the same! Took the back cover off, and removed the trackpad flex cable from the logic board. Then used isopropyl alcohol with a tooth brush to remove debris, and prevent any other particles like the strings from a swab to stuck in it. It works, and hasn’t failed me again

I have had the same problem and I have find the solution... I was ready to restaure an old back up from time machin. To do so, I have before clean the desktop. I classified and removed all the desktop documents and restart the computer. Miracle, my macbook worked fine again. I think a document on the desktop was the cause of an interference with the keyborad and trackpad.

Had the exactly same problem with some macbook air 13" and it was finally hardware problem, replaced trackpad + flex cable and got fixed (did clean reinstall of everything software related and didnt fix it still worked in login screen)

I had recently installed nvidia egpu driver(https://egpu.io/forums/mac-setup/wip-nvi...) which was causing the issue. Uninstalling it fixed the issue.

Thank you to @jesan90 and @Denny Glover.

My keyboard and trackpad worked at login screen, and stopped working after logging in. I tried all software fixes and gotten no result. Then I opened the back cover, took out the battery and unplugged the trackpad flex cable. I saw some ports had turned black. I wiped it with alcohol, put everything back together. Then it worked!

I was searching for how to assemble a MacBook and found this video. This guy had the same problem and did a demonstration of how to change the trackpad flex cable. In my case, I didn’t have to change the cable, simply wiping the ports with alcohol fixed the problem.

https://www.youtube.com/watch?v=BGPsUTWG...

I solved the issue on a Macbook Air mid 2013. TL;DR at the bottom.

The Air had I started off by verifying that a USB keyboard and mouse would function. Then I did a Time Machine (System Preferences/TimeMachine) backup because that’s the first thing I do on all customers macs that involve potential changes. Then I turned off FileVault (System Preferences/Security & Privacy/FileVault). That took many hours. Reason I turned of FV is because when I would reboot the system I could use the keyboard and touchpad on the Air. After logging in they would stop functioning. Hence I thought it was a software problem.

Then I updated from Yosemite to High Sierra to Catalina (cause it should be updated anyway). After that didn’t solve the issue I checked the Accessibility (System Preferences/Accessibility/Keyboard|Pointer Control) options for both mouse and keyboard. Mouse Keys and Sticky Keys were not turned on.

Then I moved, not deleted, the Users Preferences folder. Upon rebooting MacOS rebuilt the users preferences as if it was a new user signing in. Still not working I copied the old preferences back to the original location and skipped the existing files.

Next I tried booting to Catalina Recovery Mode via Catalina USB installer (make a Catalina USB installer, plug it in and hold the ALT key prior to boot chime of macbook). Had I done this in the first place I would have realized that the keyboard and trackpad also weren’t working in recovery from a different device, which is a big clue. Upon realizing this I decided to check the hardware more closely.

TL;DR: Initially I opened up the Air to verify that cables were ok and plugged in. Should have checked closer because upon removing the IPD Trackpad Flex Cable (under the battery) I noticed a small amount of corrosion on the trackpad side of the cable. I cleaned it with isopropyl alcohol and a toothbrush and let it dry. I also gently scrubbed the connecting ports. I didn’t find any other corrosion to lead me to other future problems (whew). Putting it back together the keyboard and trackpad started working 100%. Because I don’t trust corrosion I convinced the customer to get a replacement cable anyway.