keyboard does not work when using filevault

kind of strange !

my keyboard just had a problem of lagging and not properly working when using file vault to the extent of not letting me log in.

I deactivated file vault and run the disk utility app to check for errors on the hard drive as suggested in a forum. Everything seems to be fine.

After running again filevault, the problem persisted and even worsened ! filevault stopped in the middle of encryption and showed a error logo which sacred me a lot !!!

I could finally reset the access using the apple id through a wifi connection. Encryption is running now an I hope someone will help me understand what was going on!

Regards,