My professor cancelled research for the summer, unsure what to do Around halfway through my spring semester (around April), I met up with my CS professor for research opportunities and he said he'd be happy to take me on for a project. He sent me papers to read over the course of the month, but also said he wasn't expecting me to finish them all since finals started in mid-May. He also said if I'm in town for the summer I can do research throughout this period.

I told him in May that I can stay for the summer by dorming here and would be happy to continue the research through this time, but my dorm wouldn't open until June 1st. My professor was fine with that and said we could meet starting then.

The first month or so was rather good; we would meet and discuss papers, he would give me more papers, etc. We even talked about me continuing this research in the Masters program if I applied and got in. However, around June 20th he just disappeared. I emailed the PhD Student under him and he told me the professor was out of the country, but he'd be happy to take questions. I went with him for questions for the rest of June, but he ended up leaving town prior to the start of July. I never heard anything back from the professor until July 16, who asked if we could meet at a certain date/time. I told him that due to my summer job I couldn't meet at that specific time , but I could definitely meet at another date/time.

I never got an email back, and with work and all I was too busy to follow up immediately. But I followed up the next week telling him my dorm stay would be coming to an end in a week and I was hoping we could meet before then or meet once classes resumed. He emailed me back saying he decided to cancel the research because his fall/summer semester is too busy and he doesn't think he can advise new students any more, and encouraged me to reach out to other professors for research.

I'm not sure if he cancelled research for another reason, or if he genuinely realized he doesn't have time for the research with new students. I feel for investing time and money for my summer to do research, for him to cancel without at least providing a reason or giving me some sort of advanced heads-up is really unfair. How should I proceed with this issue? There was another student doing research alongside me, I plan on emailing him to see if the same thing happened to him. I told my parents and they were pretty mad and said I should take this up with the school, but I want to at least clear this up on the ground before I do anything like this. I won't get reimbursed and I effectively wasted my summer (although I did make money through a summer job, so there's that), but should I just let this die or pursue it?
It doesn't really matter why he did this, and it doesn't really matter to you that it might be unethical for him to treat you this way. What you need is a solution that will advance your studies. 

I think the best advice he gave you is to find someone else. Do that. He may not be suited to advise anyone, and he certainly isn't fitted to advise you. 

You have, I suspect, made some progress on the tasks that he gave you. Talk to other professors explaining what you have done and asking whether they will take you on as a student. You can also explore whether any of the work you have done is useful if you work under their supervision. Don't press it, but it is possible you can leverage it. They know what they are interested in, and you want to become part of that, rather than necessarily continuing what you've been doing. But the work you have done can be used to show seriousness of purpose to a new professor. 

What you want in a professor is someone senior enough that he or she will have plenty of ideas, but also someone who will have the time and desire to help you advance. Very junior professors are too often working too hard to get tenure to be of sufficient help to students. But someone who advises too many students will have little time for you. 

Also, it would probably be a mistake to complain about your treatment by the other professor, except to someone of real authority. As a student, you are unlikely to know what sort of politics there is in the department and speaking out, even if valid, might do you more harm than good. All you need is a solution. Focus on that. If you need to yell and scream, yell and scream at the moon.