huge FPS problem and need help

[nicknick]

hi all i have been playing TM2 since the full game was released and i have had my graphics on all high setting with no problems at all until 3 days ago my FPS would drop from 112 to 4 and major lag i have no idea on what is going on i uninstalled the game and i tried to reinstall it a few moments ago but now also it will not let me reinstall the game it gives me an error saying a file cannot be found

any help would be nice thanks