I Etham, You could say: " I had an increase in my salary", "I had a salary increase", " I had a pay raise(American English) / pay rise (British English)".

Ethan, they are interchangeable, but the emphasis is slightly different. Usually we would say, "I had an increase in salary/ I had a salary increase" and "My salary increased" and the emphasis is that I received it, and the boss decided it. If I say "I increased my salary" (My salary, not "I increased") it means that I made a lot of effort and had control over my salary. A sales person could say this, because they made effort, and the resultant salary increase was because of them, and not the boss.

The second is wrong and the others are awkward without context. For example, if you want to announce the event of your pay recently going up, say “I just got a pay raise!” “I just got a raise” The others could be ok with context. “How were you able to move to a nicer apartment? I thought you were struggling” “My salary increased” “I had an increase in salary.” “I got a salary increase” (these sound ok because you are already talking about finances.)

It's possible to say “I had an increase in salary” and “My salary increased”. In the first sentence “I” is the subject and in the second “My salary” is the subject but both sentences share the same meaning. However, you can not say “I increased in salary” because In the first and second sentence the salary is increasing but in this sentence *you* are increasing, so it gives the sentence a different meaning and it doesn’t make sense. You can increase in size or height for example but not salary as salary refers to the money you make not you yourself.