So out of nowhere (kind of), my computers stopped recognising my NW-A55. It was actually gradual on my new Acer. If you tried different usb ports it would eventually work in one. Now it doesn't work in any. So I tried my old HP and it doesn't work on that either.
There's no explanation for it. It worked on both, and now it just doesn't. But the thing is, it charges on both. So the connection is fine. It just doesn't come up as a drive. The device stays on whatever screen it was on when you plugged it in, like it does when you just charge it. And the battery thing indicates charging. The charging light comes on.
I never changed any settings. And like I said it was gradual. It was still working sometimes, but now, not at all.
I looked in the settings and 'auto activate USB mass storage' is on. I've tried turning it off and on again. No good.
Don't know what else I can do? I've done all the simple things like resetting computer and trying every USB port etc.
I don't know if you got this figured out, but here are a few suggestions from an old tech.
1) Recheck the connection settings on the A55.
2) With a known functioning flash drive, test your USB ports on the PCs.
3) Take your A55 to another person's PC and test it there.
4) Back up your files and perform a factory reset on A55.
5) Now it gets ugly, one or the other is faulty. Either your cable (Sony WMC-NW20MU, not a regular USB cable, btw) or the actual WM-Port on the A55 is faulty.
5a) Since it sounds like the connection is half working (the charging part and not the data part), lets try a bit of preventive maintenance first. With the power turned off and the cable not plugged into a PC, blowout the dust from the WM-Port with a photo duster or some canned air. A drop or small spray of contact cleaner to the port and a bit of working the port/cable connection in and out, a dozen or so times is fine. Since this problem sort of crept up on you, the port connections may have started to slowly corrode, this little exercise may free that up. Retest.
5b) The cable is the next easiest, here is an Amazon link for a replacement,
https://www.amazon.com/gp/product/B000O2Q9DG/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1 . Retest.
5c) If the WM-Port cleaning and a replacement cable didn't fix it, then
unfortunately, it must be the WM-Port itself. In this case, unless it is still under a warranty, you are probably out of luck. Without access to or the help of a Sony service center, this could get ugly really fast. I have rebuilt plenty of laptops and phones but nothing this small, so be careful who you pick for the repair, if you go that route.
Good luck and I hope you got your A55 working, and didn't make it to the bottom of this list.