I Was On Mumble A Couple Days Ago And It Was Working Fine But Today All The Sudden Nobody Can Hear Me Ive Looked Over All My Settings Im Not Muted Or Deafened And I Can Hear Them My Lips Are Lighting Up And I Have The Latest Version What Is Going On

check:

Your mic is working

Your mic is connected to your computer

You are in a room with other pepole in it (I think this is obvious but im posting it just in case)

If not one of these im not sure.

Check to see if your mic has a physical mute button (On the hardware its self.) If it does, make sure that isn't muted... I do this to myself all the time.

Re-run the 'Audio Wizard' (Configure>Audio Wizard)

This happens to me occasionally. Ussualy closing and reopening mumble fixes the issue

Also happens to me i just go into my settings and press the apply button on the shortcut keys and it fixes it for me.

Like Yield said, but also use the Audio wizard and make sure your microphone is selected