How to find a job without recommendation letters?
The situation is difficult so the solution may also be difficult. I can offer only a few suggestions. 

If you are just four years past finishing your doctorate it isn't too late to re-connect with your previous professors, and maybe your advisor. If you wait much longer it will be, however. The best way is to visit your old institution in person and spend a couple of days talking to people and reminding them of who you are. You can also talk to them about research ideas - theirs and yours. But you can also let them know why you have been away and that you'd like to get back into academia. If you were once well regarded then you still are, but they need a reminder. Such a visit might be the best "vacation" you've ever had.

Another thing, not very palatable, is to get some low-level position in a decent university where you can do more than is required by the job. If you can let the tenured faculty know of your skills and interest, maybe you can be given interesting tasks that will lead, after a while, to good letters of recommendation. It may not be possible to work up from a low level position to a better one at that university, but you may be able to leverage it for a position somewhere else. 

Further down the list of suitable options is to look at good secondary institutions, rather than universities. There are many of them that find people with doctorates to be very desirable. The job is mostly teaching, and mostly introductory subjects, but it can pay the bills. If the place is also located close to a good university, you can make yourself known there and try to get connected to a research group so as to get some papers into publication. Initially they might be joint papers, of course. 

But don't let your age be a deterrent. You will get older no matter what you do. Many people don't start their career until your age, in fact. But take a long view into following whatever opportunities present themselves, always with a view to a higher level position.