Guitar.....?

i have an american strat and theres something wrong with my bridge... a month ago i opened it up to see what was wrong with it and i think that i messed it up more...i opened the back panel of my guitar where the springs are i took the bridge out to adjust it properly because it was outa place but ii took out one of the screws that was keeping it in place.. its now loose and my other screw is not loose it is stuck in place ...when i put my bridge back together and tuned up my guitar it was normal at first but now when i use the wammy bar it goes out of tune!! it never did that before it used to stay in itss regular tune when i used the wammy bar but now when i pull back the tuneing goes up... i was wondering how i could fix this and if there is something i could use to make the screw in my bridge not so loose thanks