You may have been trapped in the difference between "unused" space and unpartitioned space. I encourage you to not give up so quickly--largely because Linux is now so mature and MS is behaving so badly.
OK--deep breath--it is OK to go back to Windows!!
If it is getting through a fresh install, then it will install its own loader. It sounds like you might just be doing some kind of recovery or repair. Did you try fixmbr?
Push comes to shove, you may need to wipe the drive and do a fresh install. If so, make the Windows partition(s) such that there is at least 10GB left on the disk (not partitioned). Then, if you decide to give Linux another try, it will be painless.