I upgraded my system a few months ago and set up time machine to work with new system. I have an Intel Imac 5.1 and I'm using OS 10.7.5. I went to look for my backup and couldn't find it. I believe I set up time machine to save to my external hard drive with a Senior Mac Tech. When I look on the hard drive I don't see any backups after 2015. This is very strange. Could the backup be somewhere else? On my computer perhaps? If so how can I find it? I want to look at a particular file that I need. Thanks in advance for your help.