About 2 weeks ago I got a really bad virus on pc my touchpad stopped working as well as a bunch of other things so I to just reset my Toshiba satellite by holding down the 0 button at START up with my Logitech k400 wireless keyboard but since the virus my touchpad on the wireless keyboard works but the keys no longer work any help WOULD be greatly appreciated thxA virus won't affect a keyboard...PERHAPS we could ask the OP how he knows the keyboard has the virus?
The obvious is to try using a standard keyboard and see what happens.
Some time ago USA Today did an article that IMPLICATED a virus could interfere with the keyboard. The SOLUTION is to remove the virus. 

ive got superantispyware I had avg now ive Kaspersky spyhunter I spent hours and hours one day downloading anti virus programs such as malwarebytes then running a scan quaranting viruses then when that didn't fix it then id uninstall and download a different one
Did you replace the batteries ?> ?I have brand new onesTry a different channel on the reciever....move all other wireless devices away from the PC...including phones.it dosent have oneTime to replace it then...how old is it ?about 1 year