I have a mod conflict

Try removing the mods by half:

1. Remove half of the mods (including mods that depend on other mods from the first half)
2. If you don't crash, put in half of the mods you just removed, then continue adding up. If you do crash, remove half of the mods you have now.
3. Figure out which mod is causing the issue.

We don't know what doesn't work means

"Doesn't work" does not actually mean anything, explain more thoroughly. For example:

Wrong: My game crashes please help!11!1 Correct: After I installed OptiFine, my game crashes, here's the latestlog.txt. Please tell me which mod it's conflicting with.

Wrong: My resource pack doesn't show up!11!1 Correct: I installed a resource pack from (link) and I have no idea how to properly install it, it doesn't show up in-game. Do I leave it as a zip, extract it or what do I do? Here's a video of how it looks.

If you don't really know what you are doing, the best you can do is just send the log file (latestlog.txt), you don't have to say anything about it.