I  use windows as well as Linux in one laptop. I don't know what I deleted in the partition settings. Suddenly when I restarted my laptop, it showed me the below error message. GRUB loading.Welcome to GRUB!error: no such partition.Entering rescue mode...Then I tried many command keys from each partition, but it always blimps a error unknown command or unknown file system.I don't have a cd drive to backup my laptop. But I have a pendrive installed with windows file and ubuntu 12. Again I tried to recover it. But still the same and no changes.  How can I recover it? 
Recover from Grub error
linux;boot;partition;grub