You could try removing your CMOS battery from your motherboard for a few minutes, and then putting it back in. This will usually invoke the PC into telling you about it the next time you boot up, and will also give you the option to enter setup (BIOS). However only do this if you are thoroughly familiar with how to set your BIOS up, since removing the battery will set everything back to defaults, including the BIOS date and time.
Also, have you tried the Delete key after booting to see if it works in the OS? There is a small chance that the Delete key itself may have gone bad. Just find some text in a word file somewhere and highlight it and press Delete to see if it erases it. You may have to create a test word file with a text editor of Office program just to use for testing purposes.