I launched the game and as with most the first thing I did was go into the options, I changed the aspect ratio and now when it launches it flickers between fullscreen with a black border around it to windowed repeatedly before giving me a error "Engine Error Unable to set mode" . I've tried doing multiple full reinstalls and disconected from cloud before doing so in hopes it would reinstall with the default screen resolution settings without any success. is there a way to fix this?

If you choosed to keep your save(s), the saves and a file for the settings will be saved at your appdate.
By default the path should be somewhere like
C:\User\YOUR_USER_NAME\App Data\Local\Virtual Store\Program Files\
or with Win 7
C:\Users\YOUR_USER_NAME\AppData\Local\VirtualStore\Program Files (x86)\Activision\Vampire - Bloodlines\Vampire

Edit:
So you need to delete the file for settings too if you reinstall it to reset the settings.

So looking in the Vampire file is there chance you can tell me what the name of the file I'm looking for is?

That would be cfg/config.cfg...

I have the same issue except with a grey loading screen before "unable to set mode" box appears... Windows 10 and with the unofficial mod.

Have you tried starting the game in Windowed mode to see if it bypasses the error?