How do you fix a laptop keyboard? (read description)?

Ok so I have a Toshiba laptop and lately we have been finding ants hiding in between the keys. I was really grossed out so without thinking I grabbed the nearest bottle of ant killer/pesticide and sprayed it all over the keys, in between and everything. But I am only 14 and I don't know that much about computers ok! Now whenever I go to type, some of the keys, when pressed, don't only type the one letter or number as they should. For example, if I typed the letter T, on a normal keyboard it would come out as so on the screen. But on my laptop, when I type T, it would come out like this: eT5. And remember I only pressed the T key. That's just one of them. And whenever I press backspace it makes me go back to the previous page! So the only way I can delete ia to scroll over and press cut. Please help!!!