You can apply directly at a company and ask them if you can start working there (on a low level first if necessary since you have no certificates). Than you can work you way up the career ladder.
Apart from that you can also try to do a retraining (Umschulung) at Bundesagentur für Arbeit or you can try to acknowledge your existing qualification. There are contact persons for that in every city. Another way would be to do a so called “external examination” which is a test that you have to pass in order to prove that you have skills.
But generally speaking you can always start working.