SU Pro 2018 is 'not responding'

it was working smoothly until today, I can’t find the SU Pro 2018 to reinstall it.
Any suggestions where to find the download?

Search around on this forum and you will probably find a legitimate source for a 2018 download. However, I doubt that re-installing SketchUp Pro 2018 will cure whatever caused the not-responding incident.

Did you eventually terminate the SketchUp process? If so, how long did you wait while SketchUp was not responding? What kinds of operations were being done in SketchUp at the point when it became unresponsive? For example, executing some extension command or feature?

The Not Responding message at the top of the screen means that SketchUp is busy doing something and won’t respond to further input from you until it has finished. On it’s own that isn’t a bug nor does it indicate that you need to reinstall the software.

What’s going on with your model file that is causing SketchUp to be so busy?

Share the .skp file so we can see what you have going on. I’d bet my lunch money that we can help you get it sorted.