Start Windows recovery (from a the Windows 7 DVD if you have it, else you will need to search how to build one on the web), and rather than installing, let it repair your installation (that is an option available); then let it guide you: chances are good that Windows Repair will fix things automatically.
If it does not, go to the command line prompt (that is the last option in the repair menu) and run bootrec/fixmbr and/or bootrec/fixboot, depending on what you believe you broke. Then try to boot normally.
If it still does not work, there are other options like bootrec/scanos (check the report) or, if needed, bootrec/rebuildbcd, or other programs like EasyRE; but this should not happen unless your tests with Linux did include the erasing of existing partitions...