Where to start?
Changing a profession or starting a career is always about persistence and a bit of luck. It is very important to find a company that will give a newcomer a chance, they exist, the easiest way to find such a company is among small web studios or startups.
Many (including me) started with web studios and online agencies, with no experience at all, just after reading books and watching videos.
Here’s a list of companies where you can write and offer yourself as an intern or a joun.
The scheme is approximately the following: you choose a system/field/project which interests you, look for acquaintances, knock on HR people, use community (like PM lunch for example :))) and depending on how serious a downgrade you are ready to get, you offer yourself there (including through your friends).
Prepare yourself, most likely there will be a lot of rejections at first and it can get sad, it is important to prepare yourself for this and not to give up. The more fishing rods you cast, the better the chance that one of them will convert into a job offer.