My Game keeps crashing

My game keeps crashing I've deleted java and Minecraft and uninstalled it . I did download forge and mods and I got 1 to work but the rest didn't work and then I downloaded the rollercoaster mod and it didn't work I uninstalled forge and the mods but ever since then it hasn't worked
and it loads the minecraft screen like were it says singleplayer multiplayer I try to do a regular world I create it but it never loads Help please