After i deleted my Ubuntu partion my previously installed windows 8.1does not start it says Error: no such partition. Entering rescue mode... Grub rescuestack.i
Please help me am locked out of my pc
I've had this issue as well. This happens because the Windows boot loader was over written when you installed Ubuntu. You see the GRUB error because the boot loader that boots both Windows and Ubuntu was installed on that Ubuntu partition. So, when you deleted that partition, you also deleted the components of the boot loader, leaving you with a computer that won't boot.
To fix this issue, you need a Windows installation disk. If you don't have one, you can make one with a USB drive. See how to do that here: Microsoft Download Center USB tool. You will need a working PC to create this.
Boot your computer with the install disk or USB. In the bottom left corner of the windows install dialogue, you should see something along the lines of "repair computer" or "trouble shoot this pc". Click this. Then click advanced options. Select the option to open a command prompt.
Run this command in the command prompt: "bootrec /FixBoot" Then run: "bcdboot c:\Windows /l en-us /s : All"
Reboot your computer, and you should be able to boot now.