|The Windows bootloader file typically can not read a hard drive's partitions once Linux is installed. There are several solutions however. |
First and foremost, if you are able to boot windows, you will want to enter the BIOS and make sure that your Boot Load menu has your Hard Disk selected as it's first option, not Flash or CD. From there, if it is still not working, try installing EasyBCD. It's a tool for Windows to setup the boot loading screen.
If you are unable to boot into Windows and can only access Linux, you will need to edit your boot load file. Depending on your Linux distribution, you will either need to edit GRUB or LILO. Here are some basic tutorials: