blank white page after updating

For the past month, I have been adding events to our team’s website per the request of the owner. She had someone else build it over a year and a half ago and it’s been in non-use for a while. I am not sure what version it was on, but tonight I decided it was way past time to update to the latest wordpress version. I thought it was automatic, one touch and done. However, now all I am seeing is white page. No admin page, no dashboard, just blank white. Same when I try to go to website from outside using laptop.

I can access the home page using my mobile devices (cell and tablet), but when I click on other pages, they come up blank white also.

Help!!! Is there an easy fix to go back to old version? I have none of the original files, nor did I do a back up.

http://www.sparklespateam.com