2 Error messages &

A few different functions of the Admin area of my site have stopped working.

For example, I have custom menu’s that I use. I have attempted to move one of my submenu items up a slot because it was out of order. When I click Save, the entire menu disappears, is deleted, and I get a funky set of bullet points all down the right side of the website on every page. So, I revert/restore to a backed up version. Tried again, does it again.

My site itself works fine, but there are a bunch of weird things going on with my WP Admin area. I am getting these 2 error messages at the bottom of my screen:

I am getting the

Warning: Unknown: open(/tmp/sess_ee22848894927abd6f905697457fa2cc, O_RDWR) failed: Permission denied (13) in Unknown on line 0

Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/tmp) in Unknown on line 0

Please don’t answer too technically jargony, because I am rather novice a this and not too code competent, although I do follow instruction well.

Please help!

[Closed as a duplicate: http://wordpress.org/support/topic/error-message-messing-up-my-backend-plz-help-cant-work-on-site-til-resolved?replies=3#post-3802308 ]