Guys I've got the same issue, me and my girlfriend have the exact same phones a Samsung s3 Mini GT-I8190 and we both have a sandisk 32GB Micro SD
Anyways her one works great no problem, but mine kept on saying There is no memory card detected so I kept removing it and re-inserting it which fixed the problem for a few weeks. But then the error kept coming up more and more frequently until removing it and reinserting it didn't fix it anymore. I ignored it for a little while, thinking maybe the contacts where not touching correctly or something but then I started getting errors on my phone such as "The memory card is blank, you need to reformat it" etc.
I started getting worried at this stage so again i removed it and reinserted it into the phone but this time the phone didn't even detect the card. So i took it out and connected it to my PC but same problem, it wasn't even being detected. Took a long time to try and seek the card but no joy
I was absolutely devastated coz I lost so many photos and videos. I didn't even bother trying recovery software coz the card wasn't even being detected by the pc in the first place. So I got a quote from a recovery specialist and they said it would cost at least $500+ to get data back.
So I just put the memory card aside for about two weeks and just today decided to try it again...
AND IT WORKED.... managed to get all my data back safely on my PC
I have no idea why it suddenly started working but it just did and am pretty happy for that.
So yeah Im just letting you guys know if the same issue happens, maybe put your mem card away for a lil while and try it again after a few weeks and see how you go.