I have been sued for a slip and fall in a barber shop I owned in 2017 through the negligence of not reading the watch your step sign

If you had insurance at the time, then you need to notify your insurance company ASAP.  If you had no insurance, but you now have a homeowner's policy, you may be covered under that.  If you had no insurance and have no insurance now, you need to answer the complaint.  Once the plaintiff finds there is no insurance, he will lose interest.  He is also suing the owner of the building you were in I imagine, and there would be insurance there too.

If you had premises liability insurance at the time of the fall, then simply turn it over to them and they will pay for the cost of your defense.