Saying you've tried "everything you know" doesn't help us.
Tell us what you've tried, and then we won't waste your time and ours by suggesting the same things.
Which camera is this? Did it work before? Is your monitor profile OK?
The camera is a canon 50D, yes it did work perfectly before having to reinstall windows, the monitor settings are fine, every other thing on the pc works fine, all settings within LR are at default at the moment,
Keith asked "Is your monitor profile OK?" I believe he need to know if it has been profiled and calibrated with a hardware device since you reinstalled your operating system?
If not have you tried to set your monitor profile to sRGB to see if it makes any difference?
Open control panel, double click on color management.
Check the box that reads "Use my settings for this device".
Click on Add and choose the profile "sRGB IEC61966-2.1 and make it the default profile.
Also if you have a secondary monitor unplug it.
Try to re launch Lightroom and check if the issue persists.
Please reply if you need further help.
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