Why won’t my camera work right?

My canon camera works fine then at any given moment it quits. It still shows the screen but it’s like it’s frozen and I can’t do anything. I have messed around with the card slot and the battery slot and that hasn’t worked so I would give up. When I would go back to it several days later sometimes it would work sometimes not. I thought maybe it had something to do with the battery but I have changed it out 5 times with different batteries and that isn’t working. This problem has been happening for a long time. I am going out of the country soon and would like to have it working. I need help ASAP! Thanks!