Dell c610 froze at bios screen

I could get into the bios screen but I can't modify anything! I could before. What could have caused this and how do I remedy this? Thanks!

Sorry if this sounds daft, but if you cannot change anything you are probably not supposed to!
Does this mean that no keyboard functions are working or is everything otherwise OK?

The keyboard works.... unlesss!

Maybe I disabled it?

Maybe a USB keyboard will work?

If you can get into the BIOS using the keyboard, then the chances are that the keyboard does work. Plugging in a USB k/brd may not work depending on whether the USB devices have been enabled at BIOS level.
You don't tell us if you can use the laptop as normal once the system has booted - this would help!

I can use the laptop. Everything's normal. It's just modifying the bios. I installed a ps2 keyboard and I still can't modify....

probably, you have the admin password in your machine.
use Alt+P combination to go to security page and check the pasword presence.