My galaxy s6 edge stopped charging fast and computer couldn't see the device anymore.....what do I do?

Solution
Are you saying it stopped charging 'quickly' so that it is taking its time to charge? Or are you saying that it is no longer holding a charge for long and you only recently got the device?
Well over time they do that. Especially if the battery had been in it a while. It can be either the charger cord itself is starting to go and needs replacing, the battery is starting to die and needs to be replaced, or the port where you connect it was damaged and that would either need to be replaced or you would need a new device.