Finder is not responding

A computer restart is normally the first step, which you have done.

Might be a corrupt .plist.

Do a backup, preferably 2 backups on 2 separate drives.

Go to Finder and select your user/home folder. With that Finder window as the front window, either select Finder/View/Show View options or go command - J. When the View options opens, check ’Show Library Folder’. That should make your user library folder visible in your user/home folder. Select Library. Then go to Preferences/com.apple.finder.plist. Move the .plist to your desktop.

Re-launch Finder by restarting the computer and test. If it works okay, delete the plist from the desktop.

If the same, return the .plist to where you got it from, overwriting the newer one.

Thanks to leonie for some information contained in this.

You are welcome. Do you have Google Drive installed?

Finder – Fix Google Drive Problem

Try running the combo update. It installs all previous updates plus the new one, which can replace any files that may have become corrupted.

10.9.5 Combo Update

Try running this program and then copy and paste the output in a reply. The program was created by Etresoft, a frequent contributor. Please use copy and paste as screen shots can be hard to read. On the screen with Options, please open Options and check the bottom 2 boxes before running. Click “Share Report” button in the toolbar, select “Copy to Clipboard” and then paste into a reply. This will show what is running on your computer. No personal information is shown.

Etrecheck – System Information

You are welcome. Normally it is better to fix problems before upgrading, but sometimes upgrading is better. If you are using Google Drive, I've seen no complaints in the El Capitan community.

Yosemite has problems with the current Google Drive. Also, unless you have previously downloaded Yosemite, it is no longer available.

Sierra probably won't be available until Oct, 2016.

If you want to upgrade, El Capitan may be your only option.

Check to make sure your applications are compatible.

Application Compatibility

Applications Compatibility (2)

El Capitan 10.11 Compatibility information

Also check to make sure there is a compatible driver for your printer.

Do a backup before installing, preferable 2 backups on 2 different drives.