Macbook Internal Mic Not Working!

So, I recently purchased an early 2008 white Macbook from eBay. I'm really happy with it, it all runs smoothly and it is in great condition. However, when I tried to Skype with my family, they couldn't hear me. So I went through all the system preferences for sound, speech, MIDI setup in utilities, PRAM and SMC resets, to no avail. After e-mailing the person I purchased it from, they informed me that they have never used the microphone so they had no idea if it was working or not before they sent it to me.

After finding various posts on different forums which have been left unanswered to a similar problem, I'm at a loose end. I'm not a huge techie and especially new to macs so I can't identify if it would be a hardware/software issue.

So here I was hoping to get some further suggestions or help. I've tried using a basic earphone/microphone that works with my iPhone but won't work on here. When I slide the input volume control on system sound settings, it appears to, briefly, light up some of the volume blocks, but it won't pick up any of the sound that I make. Also, when I tap next to the mic or to the left of the trackpad, it seems to also create some movement, but still nothing as to responding to my voice...not quite sure what this means but could be helpful information.

I have a 2.1GHz intel core 2 duo, 4GB ram, os x 10.7.

Please let me know if you need any more info and I will be extremely grateful for any information and or suggestions you may have

No suggestions at all?

My phone headphones with mic (no official Apple headphones) that work with my iPhone won't even work and I've tried both the input and headphones plugs.

Really don't know what else to try or where to go next. Would a USB mic work?

When you select sound from system preferences then select input and speak does it show your voice by bar movement.

No, it doesn't respond to any noise at all.

I have already tried what was posted in response to that questions, as well as the video link. I guess I should just take it to my local Apple store and get them to take a look...

dictation and speech somehow fixed it?

Hi! I made an account because I had what sounds like the same problem and somehow either updating to the latest software (yosemite as of now) and/or opening up dictation and speech has fixed it for now. I have no idea why. But if anyone else has this problem you might as well try it if you haven't already.

I was on skype with a friend, hung up, went to go do something else without moving my laptop at all, and then when I tried calling him again when I got back he couldn't hear me at all. I went to sound under settings first and it couldn't pick up my voice at all even though input volume was on full blast, but it could pick up if i tapped the mic with my finger. So I looked around the internet and did an smc restart, messed with terminal, messed with audio midi setup, made sure nothing was on mute. I didn't have any other mics to select other than the default so I couldn't switch that around. Finally I decided to try the free upgrade to yosemite. At first it still didn't work but then I randomly opened up speech and dictation under settings and it was all working perfectly again and I could talk on skype. BUT when I opened up sound prefs again it stopped working. Opened up speech and it was working again. Perhaps somehow those two panels turn something off and on? Very strange. Anyway I hope this isn't too incoherent as my coffee still hasn't kicked in yet but I hope this helps someone and maybe someone knows why this could work.