Depending on where you live (residential - urban or suburban, country - close to town or far out) one thing you can do is get out and walk around your neighborhood. Unless you have a physical issue that prevents that (I have arthritis in my hips so no walking around for me! ) it is one small step that doesn't involve the stress of meeting new people.
If you do this on a regular basis, you may start to see the same people over and over ... after a while nod and smile, then wave, then say Hi, then strike up a casual conversation ... as you are comfortable with the earlier steps. Maybe you never get past the nod and smile ... it's still a human connection.
If you are stuck at home call local community organizations and volunteer, explaining that you lack transportation, but would like to help - can they arrange transport?