You may not have uninstalled the Windows service before closing the control panel.
You did install it into the root of a drive or partition like C:\ so you have c:\xampp installation folder?
You could use the version 3 control panel found in the xampp installation folder:xampp-control-3-beta.exe
The latest version download link is in my signature.
Simply extract all the files from the archive to the xampp installation folder and overwrite when asked.
Then right click the exe file to run as administrator and to create a shortcut to the desktop, for example, for easier access.
This version has more detailed log window and it might give you/us a better idea of what is happening, plus it has many more useful features.
Let me know back what the log window gives you - you can right click on it and copy and paste.