Why is my Gmail account all jumbled up. The main Inbox 90% of the emails are missing and the created categories are jumbled up?

When I opened Up my IMac yesterday and went to Gmail inbox 90% of my undeleted emails were missing. Further some emails in the category boxes were not suppose to be in those categories. So it appears that not only are emails missing in the in box but other emails have been jumbles in the various self created category boxes.