Internal microphone not working

I have an Inspiron 1750 and my built in laptop doesn't seem to be working on skype/Facebook video chat/tinychat. I've downloaded the audio drivers for my laptop just yesterday from the dell website and it still doesn't seem to be working. I've ran dell diagnostics yesterday as well and nothing was detected to be wrong. I've also tried running the dell fixit app and everything seems fine, they can't detect what's wrong. All my mics are enabled under RECORDING from the SOUND window. My boost levels are also at 20. What else am I missing? And how do I know if this is a hardware problem? My speakers and webcam are working perfectly fine as well. Please help asap! I'm also running on windows 7 home edition 64-bit.