If you had windows and linux in your system as dual booting,, and if you have re-installed windows for any reason,.. Now for sure, you cannot boot into linux.. Windows will not show a boot option for linux/windows, but it boots directly into windows.. This is because windows cannot recognize linux boot loader and it overwrites it..But Linux can identify both the boot loaders,. So if
you install windows 1st and then linux,. Then no problem...
Here i will tell you how to restore the GRUB (it's the reason why u saw a boot option before)
1-- 1st you need the live cd of LInux. If you don't have one,... see THIS
2-> BOOT from the linux live cd/usb
3-> Open terminal.. Type the following 3 commands
NOTE: hd0,0 means 1st hard drive and 1st partition. Change it according as in which disk/ which partition u previously installed Grub/Linux
1. sudo grub ---> This command will take u to grub prompt
2. root (hd0,0)
3. exit
4-> Remove the live cd or usb and reboot your system....
NOW YOU CAN SEE YOUR BOOT MENU
