VAC banned, but i wasnt hacking.?

ive been playing new vegas and garrysmod singleplayer most the time on steam then today i was like hmm maybe ill change it up and play a little mw2 and then BAM! VAC banned, i havent played any vac secured games in forever and i havent even been hacking im certain steam wont help me they dont care, is there anything i can do? i have 100s of dollars worth of games on that account and ive never even hacked.