How to get into music with no musical ability
Oddly enough plenty of people have achieved great things in music even though they had very little ability to start out with. If you don't believe me, listen to some of U2's early recordings - no apparent ability whatsoever, just a lot of energy. And now they are not only world famous, they have become very accomplished musicians.
The key is to realize that probably anyone can make music that is worth listening to, as long as they have sufficient determination. But where to start? That's the question.
Back in the heyday of the electric guitar, lots of people would buy an electric guitar and learn how to bash out a few simple chords. That's how many of the top bands of the 1960s got started - even The Beatles. The guitar is not a difficult instrument to play to a simple standard, and once you have mastered the basics, you can create original music, perform and record.
Today's equivalent of the guitar is probably loop-based sequencing. It is easy to get started with suitable software. The trouble is, it is very easy to create music with little or no originality. This route is, I would say, almost bound to end in disappointment.
I would also say that loop-based music in general has now become available to 'the masses' and it's difficult to make an impact no matter how original your loop manipulation techniques. So, short of going out and buying a guitar, what can you do?
Well I would say that there are still many opportunities available in music for TV, either commissioned or in the form of production music libraries. Much music used on TV isn't actually 'music', in the sense of notes and harmonies. It is more along the lines of 'soundscapes', which are not musical in the conventional sense, although they are treated as music and paid as such.
So if you really think you don't have any musical ability, this could be the way to go. There are plenty of software synthesizers that allow the creation of soundscapes, often through digitally-modeled analog synthesis. You can also use original samples and processed sound sources. Gradually you will find that more notes, melodies and even harmonies are creeping in and after a while you may even find yourself becoming a 'proper' composer.
The key to all of this is to believe in yourself, and make a start right now. The journey of a thousand miles starts with a single step. An old saying perhaps, but true.