Hello Munir Dabaghi ,

It's always best to include the full error stack (and the actual version of Studio you are using), as this can provide further information- 

https://community.sdl.com/product-groups/translationproductivity/w/customer-experience/4159/how-to-get-help-quickly-in-the-sdl-community-technical-forums

In this case -

Navigate to the following folder C:\Users\username\AppData\Roaming\SDL\SDL Trados Studio

Rename the 15.0.0.0 folder ( to 15.0.0.0_old)

Re-start Studio and check if the issue still occurs

There is also an app available that you can use to reset Studio-

https://appstore.sdl.com/language/app/sdl-freshstart/876/

Thanks Steven. I was able to restore Studio and completed my work.

Best Regards and thank you again.

I also was able to restore it to normal and completed my work. THank you!!!