There are quite some ways you can build up a social life again. I had the same problem some time ago; here are some ways to make friends. I know you've tried a couple of them but I'll just add them to the list anyway.

1. Do a part-time study at some adult school. Do a 3 or 4 month eduction course (not a full education... looks good on your resume).

2. Join a social sports club, or gym/fitness. Another idea is to go walking/backpacking and meet people with the same backpacking interests.

3. Do a workshop about: cooking, painting, playing a instrument, etc.

4. Go out to bars/clubs. Difficult one if you're alone, but if you feel comfortable by yourself this is an option.

5. Meet people anywhere, in shops, on the street, library, anywhere really. This one is more difficult by yourself, but perhaps a special turn of events will bring you together with some folks.

6. Go to casinos to play some cards. Perhaps there you'll meet some people.

7. Do social volunteering work, where you work together with other volunteer.

8. Go to a church weekly every Sunday, and hope there are people of your same age there.

9. Lastly, you could contact some old friends and spend time together, and also meet their friends and friends of friends, etc. But sure to get their phone numbers if you've spend some time together.

This is how I met some friends of mine.

If you need to refresh your social skills, an idea is to read some social skills/conversation/communication books. Search for them at amazon.com or barnes-n-nobles or some other online bookstore (local bookstores usually have a limited amount of social skills books). One book I can recommend and that's very practical is called: "first impressions - what you don't know about how others see you".

I feel I've left out some other options of meeting people but this is what I could think of. Good luck with building a social circle again.