Cards do wear out so you pop in a new card, format it and restore from backups. Android is just like Windows in this regard. We only lose what we don't backup.
It can really upset folk that the card works elsewhere but cards are cheap. Pop a new one in and if you want to try it, duplicate the old card onto the new card.
So...Here's what's been happening with me. Ive had this phone and this SD card for about 2 years. But then all of a sudden when moving an app over to it, my phone said to "Unmount the SD card before removing it". The thing is, I hadnt. So I tried restarting my phone. It recognized it for literally less than a second (storage and all) before saying that same message again. I tried removing it, then putting it back in. Same thing. So then I thought, "Well crap, it's broken". Just to make sure, I tried it in another person's phone, and it worked. Then I tried theirs in my phone, and it worked, too. At that point the only thing I could think of doing was formatting it. I had to do it on the other persons phone because A) Mine wouldn't recognize it and B) We didn't have an adapter for USB. Now, here's where it gets EVEN weirder. I had seen earlier that 12 gig was used on it. When we went to format it, it said 11 gig. I just brushed it off, and formated it anyway. When we went back, instead of being empty, it said 12 gig was on it now. We tried it over and over, including deleting it manually and formatting it, but still it showed 12 gig. So yeah I don't know where to go from here. Just in case the info is needed, it was a 50 gig SanDisk Ultra microSd, and my phone is an HTC Desire 626s. Please help.

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