playbook screen touch is not working, so I can't login in to tablet.

On some tablets you can plug a keyboard and mouse into the USB port and use them, but I've just tried it with my Plabook and unfortunately it doesn't seem to work.

If you follow the guide BlackBerry PlayBook Front Panel Replacement there's a small chance that you can fix it by reseating the digitiser cable. I think it's the connector next to the QR code in Step 17.

If that doesn't fix it, with a bit of hunting you should be able to find a replacement digitiser on eBay and follow the rest of the same guide to replace it.