I agree,my OH got a new laptop and was in the process of transfering all the folders with photos in on to it.
The new laptop went wrong within two hours (software fault) it had to be sent back,where they completely wiped it back to the original settings
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He didn't tell me for ages that my oh so precious photos of our sons uni graduation day were some of the first he had transferred
they weren't the bog standard shot of son with scroll in hand they were group shots of all of us,and family shots of the celebratory meal afterwards,around 100 in total.
To say i was upset was an understatement,he hadn't backed them up when i had kept asking him to do so,he was moaning he had lost photos too,poor him,losing pics of bearded dragons,gecko's and suchlike that he had bred,well i'd lost pics of a HUMAN i'd bred,i think that's more important
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My other son (not the one in the pics) has thousands of pics on a huge external hard drive,while browsing he found the uni graduation pics,i was ecstatic
So like the OP said,take a few minutes to back up your precious pics,i was lucky,you might not be.