Possible causes of read-only mount: (1) Security configurations on the Operating System; Too many to list, but they are altered using Windows Registry; Google around; (2) Corrupt Filesystem / Dirty Bit set; Use chkdsk; (3) Corrupt partition table; Use a drive partitioning utility; Pendrive will be erased but will be usable later; (4) Pen drive microcontroller reporting faults; It means it’s time to buy a new drive. I’m still looking into possible temporary fixes to make the drive last a few more days, but it looks bad.