Is it correct? I "am trying fixing this"?

If the verb to try is being used in the sense of to attempt, then it is generally followed by to + infinitive rather the -ing form of the verb. So, assuming that the trying here is attempting, it should be:

• I am trying to fix this.

If, on the other hand, the verb is being used in the sense of testing something out (e.g. to see if it works or if you like it), then it is usual to follow it with the gerund:

• I'm trying wearing contact lenses (to see if I like them).
• I'm trying drinking milk before bedtime (to see if I can cure my insomnia).

However, the difference between the two senses of try is not always so clear-cut. A popular song from poor Alicia Keys has the lines:

Have you ever tried sleeping with a broken heart?
Well you could try sleeping in my bed.

where the first try seems to mean attempt and the second means test out.

[And Irene is right that consecutive -ing forms can sound a little awkward.]

Although it is possible to have an -ing form after the verb try, two consecutive -ing forms sound very unnatural, so you'd better avoid it.