Re-installed DW20, most sounds not working

[PhilHibbs]

I had a problem connecting to a server, it was saying "Forge Mod Loader has found world ID mismatches; ID 1252 (ModID: WR-CBE|RedPower, type rpwireless) is missing" so I re-installed DW20. I made a copy of my save, deleted everything except for the FTB_Launcher.exe, and let it reinstall itself. Connecting to the server is ok now, but I got no sounds apart from when I go through a PortalGun portal. I restored my SSP world, and I get the same.

These are the sounds that are working: Portals, Sentry Gun chatter, and Advanced Jetpack, Sword of the Zephyr wind.
These are not working: Pressure plates, buttons, doors, cows, chickens, zombies, zombie Pigmen.

Basically, mod sounds seem ok, but vanilla sounds are all not working.

Any suggestions?

 

[Whovian]

For some reason, I sometimes get that, messing around with the sound settings and waiting usually fixes it.

 

[Juice57]

Check the resources folder and see if the files are even in there.

 

[Greevir]

The sounds from minecraft sometimes take time to be copied from the jar to the resources folder. Usually when doing a fresh install, I just keep pushing buttons in options till I get sound.