Photoshop not opening

Hi, 

I have been having issues regarding my photoshop for the past few months. This began with the software suggesting my scratch disks were full, despite having over 20GB remaining on my laptop and not running any other programmes apart from Lightroom. I was able to edit images if I previously opened or used these files, but not able to create 'new' ones. 

Yesterday, I tried to open as usual. But, it just continued to crash and not allow me to do anything. Coming back to my computer today. I had to force quit the application, it wouldn't let me do this for some time. Now, if I try to open the programme at all it comes up with an error pop up saying 'You can't open the application 'adobe photoshop 2020' because it's not responding. I have tried to uninstall and reinstall the file and it's still not working. 

Any ideas on how I can fix this? 

I am using a Macbook Pro 2.3 processor with 8GB memory.