Revit Tooltips showing weird characters

Revit tooltips show odd characters when you hover over icons.

This can be caused by a number of things but the one that fixed our issue was to just uninstall and reinstall Revit. There are still other factors so I have outlined them below.

• Check the desktop shortcut and make sure the target has ENU after Language. Right click on the desktop icon and go to Properties. Example from my desktop shortcut: "C:\Program Files\Autodesk\Revit 2019\Revit.exe" /language ENU
• Navigate to the C:\Users\your user profile folder\AppData\Roaming\Autodesk\Revit\Autodesk Revit 2019 or whichever version you are using and open the Revit.ini in Notepad. Search for the line Language and make sure below it shows ENU: * AppData is a hidden folder. Here is Microsoft's steps on how to show hidden folders https://support.microsoft.com/en-us/help/14201/windows-show-hidden-files

[Language]

Select=ENU

• Reset the Revit user interface by deleting the UIState.dat found in C:\Users\your user profile folder\AppData\Roaming\Autodesk\Revit\Autodesk Revit 2019\ENU. Make sure you create a backup by copying the UIState.dat before deleting. 
• Reset your Revit to default by following Autodesk steps: https://knowledge.autodesk.com/support/revit-products/getting-started/caas/simplecontent/content/autodesk-revit-reset-settings-to-default.html
• Remove or uninstall any add-ons that are not native to the Autodesk software.