How I can repair my software

You'll need to access the Realme site here: software update

@sukhjinderkaur that will depend on what is going on with your phone. If it still boots up but lags or freezes or your Apps are crashing you might just need to do a factory reset. If it is stuck in a bootloop (hanging on the realme logo), you will need to do use the stock recovery steps. If it is hard bricked you will need to reflash your phone. For the reflash check on here

To do a factory reset:

• Turn your phone completely off
• Press and hold both the Power Button and the Volume Down Button at the exact same time
• When you see the "realme" logo appear on the screen, let go of the buttons. Look at the bottom left corner of the screen, it should show a message that says "Recovery Mode."
• On the language selection screen, tap whatever language you are using. You can also use the Volume buttons to highlight your language and the Power button to select it.
• Next tap on Wipe Data ==> Format Data. A 4 digit code should pop up on the screen. Type that code in, tap Format, and let the phone run its wipe cycle.

Since the OS rebuilds the base directories it will take a couple of minutes (~10min) for the initial screen to show up.

Just remember that a factory reset erases all of your data. That includes your photos, music, contacts Apps etc. You also have to make sure you know the password to the Google account that was used when you first set up your phone. Without that you will not get into your phone since the Android FRP requires this to allow you to use the phone.