If you want folks to help out, they're going to need more information, as much as you can provide.
- What OS are you on? Windows, macOS, Linux?
- How did you install the mods? The more detail here, the better.
- Are you launching the game via Steam, or directly?
- When you try to start the game, does anything happen? Or is it just no reaction whatsoever?
- If you navigate to the game's files, what's in there? (I'm going to guess you're using Steam. To find the game's files, right-click the game in Steam, click Properties -> Installed Files -> Click the "Browse" button at the top right)
- If you installed SMAPI (and you should have) and followed its instructions (ditto), you should have filled in the "Launch Options" field in the Steam Properties dialogue. If you clear that out, and try launching Stardew again, does that work?