ERROR "Upload Directory Doesn't Exist" - tried everything with no resolution

I'm nearly done with a project and everything was working just fine. This morning I go to make a couple changes to my project and none of the pages will load. I login to the CMS Builder and see that there is an error "Upload Directory Doesn't Exist." I go to check the directory in the CMS and it's there, along with all the photos. I go into one of the pages in the sections editor and click on the "upload" field, then I resetting the directory path and folder path. Still the same problem. Then I delete the "upload" field and make a new one, checking "Use custom upload directory" and reset both the directory path and folder path. Still the same problem. I will be contacting the hosting provider to see if there are server changes that caused this. Otherwise, any thoughts??? I have a deadline and I don't have any clue as to how to resolve this problem. To my knowledge, nothing has changed and it was working just fine last week. All the directories and CMS seem to be in place, so I don't know why it's generating this error. Please help if you can!!

Update: I called the hosting package and no server changes were made recently. I checked the permission settings as well and corrected a few but that still didn't make a difference. What do you think changed from last week to this week to cause this problem?