dudes it keeps on getting stuck on the loading screen on the launcher it will say "launching" and stay there

Put the summary of the bug you're having here

What I expected to happen was...:
to open after loading

What actually happened was...:
the first time it told me net.minecraft.mian.main was not located or smthin
then i got stuck on launching

Steps to Reproduce:
1. idk
2. idk
3. idk