This is a quick guide for those that do not know how to Verify Integrity of Game Files aka Verify Game Cache.
Reasons to want to verify your game cache are ways to clean out unwanted files, that may be causing you issues. This also helps when you are having trouble joining servers at times. Let's get started.
Go to your steam library and find 'Unturned'. Go ahead and right click to find properties, Click it!
Head over to the 'Local Files' tab at the top of the new screen that pops up. You'll be looking for a button towards the bottom of the tab that says 'Verify Integrity of Game Files' go ahead Click it!
Grab some popcorn and a drink and let the small download play out!
Go ahead and launch Unturned again and see if your issue was fixed, Hope this helps good luck!