Was there something about the bike that you didn't like when you did ride it several years ago?
Would it still suit the type of riding you wish to do now?
If there wasn't anything that didn't work properly or well about it years ago, and it would still be suitable for you to ride now, then I would just get it back into proper working order as it is.
If you don't want to do it yourself, then I would take it to your local bike shop and have them go through it. It will probably at least need to have hub bearings cleaned and repacked, cables adjusted, new tubes and tires, etc. They should be able to give you an estimate of what needs to be done and the cost.
Then ride it for awhile and see how it feels.
You might decide to change out those platform pedals for clipless pedals, or want a different saddle, etc.