Help !!! i think my computers hacked !!!?

ok this started last week i was playin an online game wen suddenly my computer back spaced and bleeped so i played the game again and it backspaced again ! now i cant controll my mouse cos everytime ui move it my computer bleeps ans the mouse moves all over the screen and i cant click anything , and wen i finally got onto youtube website yesterday my mouse froze but the internet was still running , wat the hell ias going on i scaned my comp 4 viruses but nothing was detected!