Can't reinstall osx, messed up partitions.
During an installation of windows through bootcamp, I had to quit it due to an error. This resulted in a 200gb partition of my HDD to disappeared from disk utility. I eventually found it through the terminal but when I tried to merge it into my primary partition it disappeared with no trace even when using diskutil in the terminal. After reinstalling and attempting to fix the missing data with the terminal; I am at a point where I am stuck at the cmd+r boot menu unable to install osx due to the installer giving the message of "This disk cannot be used to start up your computer", as well as having 200gb of my hard drive missing.
Any help would be greatly appreciated thank you.
iMac, iOS 11.1