-try pressing both the left and right control keys at the same time. Or power cycle the machine (full shutdown and back on)
guessing that the keyboard BIOS is confused and missed a release of a state key (alt, shift, control,...) so it acts like you are holding down two or more keys at a time.
- often hitting both left and right control key will fix this in some keyboard's BIOS.
or maybe you do have a stuck key and have to clean out your keyboard with a compressed air can