Can I fix my mom’s papers who is currently in Mexico if I am a 24 year old citizen?

Generally, a U.S. citizen age 21 or older may sponsor a parent for U.S. immigration in the Immediate Relative visa category, and if the parent is located outside the U.S. then the process to be taken is known as "consular processing." Of course, many other details determine eligibility. It would be wise for you to consult with an immigration attorney who, after learning all of the relevant information, could advise about eligibilities, options and strategies to attain your goals, and who then could offer legal representation in the often complex application process.

You may be able to do so, if she has never been deported from the US or otherwise violated US or Mexican laws.