Help on recover partition table

When I was installing Linux (Ubuntu) on a Windows machine, I accidentally (and stupidly) press the button "creat new partition table". Even though I immediately quitted the installation, now the machine cannot find the Windows system (or any system).

Do you have any suggestions on how or if I can recover the partition table and the Windows system or even just retrieve some of the files? I have data and codes that I hate to regenerate on the machine.

thanks a lot.