BOOTMGR Is Missing Issues

OK, so I have been trying to delete a partition from my hard drive, and I have been unsuccessful. But I was reading online that you can't delete an active partition, which is what I was trying to delete. So I marked my other partition as active, and rebooted. But now, when my computer comes on it gives me the error BOOTMGR is missing, press CTRL blah blah blah. My computer did not come with a Windows 7 install disk, it was pre installed. All I have is a Windows XP, which I tried to use to install Windows 7 on a flash drive to boot and access Startup Recovery. My actions have been to no avail, because for some reason the Windows 7 iso I have downloaded is, according to Microsoft's program for booting Windows 7 from a flash drive, not an iso file, which it clearly is. Any ideas about my dilemma?

The Active flag points to the System partition which is what holds the boot files and boots Win7. You can't just change the Active flag without moving the System boot files too. Did you think about asking first before randomly changing things?

To do the necessary repairs now you'll need to use another PC to download and burn to DVD or write to flash stick the latest official Win7 installer for your licensed version, from Steps 1 and 2 of Clean Reinstall - Factory OEM Windows 7.

Boot the installer, at first screen press Shift + F10 to open a Command Line, Mark Partition Active the Win7partition or 100mb System Reserved partition (preferred if you have it), then close the Command Box, click through to Repair My Computer on second DVD screen, run Startup Repair - Run up to 3 Separate Times.

If this fails download Partition Wizard bootable CD ISO, burn to CD using Windows Image Burner or write to flash stick using Universal USB Installer, boot the CD, post back a camera snap of the drive map showing all listings. Screenshots and Files - Upload and Post in Seven Forums - Windows 7 Forums

You can also use PW Set Active/Inactive partition -Partition Wizard Video Help
and then Partition Wizard Rebuild MBR - Video Help. This may be enough to do without the three Startup Repairs.

Great thanks, I used the Partition Wizard because it was easier. Now, another question. How would I go about deleting the other partition now that the option is greyed out?

Please post back a screenshot of Disk Management - Post a Screen Capture Image
which will tell us what we need to know.

If it's not yet booting then take a camera snap of PW drive map with listings as requested.

Ahh, sorry for the late update. I used Partition Wizard and everything is good.
Thanks for all your help, especially the links!

Sounds good, but it would still be best to post back the screenshot because we almost always see something that needs attention.