I can not save an image

Hi, did you check this help page? https://helpx.adobe.com/nz/photoshop/using/saving-images.html

What does the message say? 

What have you done for all-purpose trouble-shooting so far? 

Restoring Preferences after making sure all customized presets like Actions, Patterns, Brushes etc. have been saved might be a good starting point:

https://helpx.adobe.com/photoshop/using/preferences.html

https://helpx.adobe.com/photoshop/kb/basic-trouble-shooting-steps.html

https://helpx.adobe.com/photoshop/kb/troubleshoot-crash-or-freeze.html