Micraphone Not Working

I use skype to contact my ,late wifes ,folkes in the USA and the PC mic's stopped working for no reason I can discover.I have gone through Sounds and Auto devices,changed the headset and covered the skype tests to no avail. Updated drivers etc.and I am getting more frustrated by the day.
Can anybody help,could it be a hardware problem ?

Medion 8386 desktop ,2/3 yrs old Windows XP SP3 AGK Vidiocam Headset.Speakers and everything else O/K

 

Since my last post,having covered everything with no success, I used a bluetooth headset to get me by on Skype.
Decieded to look inside the PC this week and wiggled the connections to the back of the block.housing the mike and audio sockets and we are now working again
Obviously was a bad connection.