I am retired with a new computer and a lot time. I used to be a musician (40 years ago) and I don't have any skills left but I thought I might enjoy playing music on a keyboard (or other device) hooked into my computer to generate the background or other instruments.
I have no idea how to get started nor what kind of hardware or software to get.
Can anybody help???

Welcome aboard Dan. I'm sure you'll find a great deal of help within this Forum from a variety of knowledgable individuals.
Myself, I don't use a computer in my recording, but I just wanted to say "Hi!!" http://sh-boom.freehomepage.com/index.html

If you don't already have a sound card with MIDI support, you'll need to get one. On board sound will not work. For convenience and price, a creative labs sound blaster will get you started. Then get a midi controller. for under $200 you can get a 49 key controller. Also get the midi cable to connect them up and you're on your way.

Hello and welcome to the synthzone . Depending on what kind of computer you have , that will dictate what is available for you . Like if you purchased a MAC or windows machine . I prefer Mac . The basics are pretty much the same though . You would want to get a pro quality Midi and Audio card . The M- AUDIO AUDIOPHILE 2496 is a great low cost pro quality card , less than $200.00 and it works with MAC and windows machines . Audio programs for MAC - LOGIC AUDIO , CUBASE , PROTOOLS , OPCODE STUDIO VISION , NEUINDO , BIAS PEAK , TC SPARK . Windows programs - CAKE WALK SONAR , SEK-D , CUBASE , PROTOOLS , COOL EDIT , just to name a few . Just about all of these offer AUDIO and MIDI sequencing . No matter what kind of machine you have , you would want to have more ram , atleast 256megs of ram . Ram is so cheap for computers now that it's no problem to upgrade . Software synthesizer programs like REAKTOR , VIBRA-9000 , RETRO AS-1 , MODEL E , PRO-52 , SUPER COLLIDER , GIGA SAMPLER , just to name a few . To be honest there are a lot of programs available , the fun is to experience as much as you can . You are getting into a whole new world of music , you have a lot of fun just waiting around the corner .