Hi,
We're sorry about the trouble with color of the workspace in Photoshop. Would you mind sharing the version of Photoshop you're using? Did you select a preference or something happened after which the workspace turned blue?
You can try to reset the preferences of Photoshop using the steps mentioned here: https://adobe.ly/2Qzc0K3
Please backup your settings prior to resetting the preferences. You can check: https://adobe.ly/2vNz6FG
Let us know how it goes!
Regards,
Nikunj