Grub Installed On Hard Drive after ElementaryOS Install on USB?

This is my situation:

• I put the ElementaryOS iso on a 16gb USB


• I installed ElementaryOS on another 32gb USB via the installation process


• When the 32gb USB is not in, the machine goes to grub rescue. I have not experienced this with other distro installations.

I checked the file system via ElementaryOS and my Windows partition is still there. How can I boot into it?

Old post:

I tried to install ElementaryOS on my USB drive using the live install. Upon re-boot, I was prompted with Grub? I checked via the live install and ElementaryOS WAS installed on my USB drive. I did not experience this problem with installing Peppermint, Ubuntu, etc.

The Windows OS drive is still on the machine.

When I take out the flash drive, I am unable to view the Grub (it goes to Grub Rescue), so I'm assuming Grub is on the Hard Drive.

How do I boot back into Windows? If possible, how would I make Windows the default boot again?

I am able to use the ElementaryOS install fine from the USB I installed it on, but I would also like to access the Windows OS that's on the machine. Help would be greatly appreciated.