Anythings possible as long as you try hard enough.I think it's possible for you if your willing to put enough effort.
Is it possible to do a masters degree in another subject if your GPA was between 2.0 and 3.0?
Depends on the degree to some extent.
For example MBA's don't require a business degree to enroll in a master's program---but they tend to want proof that you will succeed if they accept you into it, and grades are a primary method of proof.
If you graduated below 3.0 in literature, you probably wouldn't be considered for admission into the masters program in math.
Yes you can do it. GPA is a part of application package, other documents are your GRE, TOEFL/IELTS test scores, letter of recommendations, SOP, work experience etc.
So if your GPA score is low but score higher in other part of your application, you can easily get a good school with scholarship for your further study