Trouble shooting - Installing Xampp 1.7.1 on localhost

Hi

I'm using my laptop as a server where I can hold all my php websites. I've used Xampp 1.7.4 which worked perfectly fine other than one of my Joomla sites didn't show up correctly which was due to the incompatibility with Xampp and the php version. It was advised to install an older version of Xampp.

I've uninstalled my old one, then installed the new one and now it's not working anymore :( I can't access MySQL.
It is telling me my port 3306 is already in use and although I've tried to fix it myself I'm getting to a stage of throwing out my laptop as my patience is wearing thin.

Would you be able to fix this for me? Maybe through remote accessing my laptop and checking why it's not working? I've got a back up of all my sites and databases and just need to have my websites showing again.

Please email me how you would suggest we work together on this and how much it will cost - an cost estimate is necessary.

Please do not just send me your CV as I will not review it.

This is urgent and I am hoping it can be solved today.

Thank you for your replies already.
Nathalie