I am a community college student in Computer Science field who likes to have good resume when I want to transfer to university, I found out this is very useful if I start to work in particular area in my field like Machine Learning, Security, Algorithm, ...and start to work with other professors in this field area like they who publish paper and conference, I couldn't find any professor in community college who works and researches in a serious field, I found out research and research assistant is not part of community college and you have to look for that in university then I started to send emails to other professors in different universities like UC and CSU and ask for volunteer research assistant but I didn't receive any useful response, some of them told me they will let me know if something shows up and other didn't answer me. Now I am getting disappointment because they don't want to give a chance to a college student because I am studying in community college but I want to know is this a common way I am doing if yes how is the correct way to do this?
Disclaimer: The opinions I'm about to express are based on my experience in mechanical engineering, as an undergraduate research assistant, a master's student, and currently a PhD student. I'm quite confident that what I'm about to say should apply to Computer Science as well, but if I am incorrect, then I apologize in advance.
First of all, it is good to see that you are motivated about research. You seem to be interested in fields that are very active today (I know quite a few colleagues that are working on machine learning for instance). Your curiosity and interest in advanced fields are admirable.
Now what you need to know, is that most professors (in my experience), hire undergraduate level research assistants with the prospect that they'll pursue graduate studies afterwards. The reason being, most fields of research are far fetched compared to the knowledge typically available at 2nd - 3rd year level, so you have to spend quite a bit of time reading literature, and your supervising professor will need to dedicate a lot of his time guiding you through it. Moreover, research methodology is very heuristic, and requires experience, because you have to solve open-ended problems. That means there is no solution in a book somewhere that you can look up. So the whole exercise is to train your mind to see a possible path to a solution that you might arrive at after months of work, with occasional milestones that tell you that you're on the right track. So this means that after months, your supervisor may have dedicated long hours of his time supervising you and have nothing to show for in return. The only consolation is if a student plans to stick around for a master's, then it makes sense to invest the time required, because you will have learnt a lot out of this process.
As a community college student, it may not be clear to the people you're contacting that this is your aim. This is due to the fact that most people view community college training as job training, not so much education that could lead to a field of research. As a matter of fact not even undergraduate studies train you for research, which would make the prospective supervisor even more hesitant. You may need to prove to them that you have a path in mind such that you can satisfy the university's admissions requirements for graduate students if it comes to that.
From what you've said in your OP, I can infer that you feel insulted because you are offering free work, and yet nobody seems to be interested. That is noble of you, but for the reasons I stated above, as far as they're concerned, statistically speaking you're likely to be more effort that benefit.
Another aspect that I'd like to touch on is the fact that your grammar is not adequate based on what is expected in academia. I'm making this assumption based on your original post, so I may be wrong if you simply wrote it in a hurry, but if your contact e-mails with the researchers were anything like it, it suggests that they'll have a difficult time communicating with you, and that is another headache for them. A big part of research is being able to communicate your work to people who are from your field, from other fields, and requires nuanced language to express subtleties that exist in most advanced scientific and technological fields. I know it doesn't seem important, but it truly is. You're expected to leave some sort of record of your methodology, present it at conferences, submit to scientific journals, and write grant proposals for which grammar and format is an easy way to dismiss applications at a time when research budgets are getting tighter.