Getting prohibited sign with apple logo on start up of Macbook pro 2012 non-retina
It's possible, though unlikely, that the SSD itself may be failing. The SATA connector is a much more likely source of failure, and commonly occurs in those Unibody models. Replacements can be found on eBay cheaply, though make sure you get the right part for your model, as they vary in length. 

You can also get a USB to SATA cable cheaply, so you can test the drive as an external, to see if it works there.