I am not sure if you are asking for alternative software to PowerPoint or helping you opening your installed copy of PowerPoint. I am not sure how to help you with the second problem, but here is alternatives to using Microsoft's PowerPoint. (Are you sure you do not have a trial version of Office?)
You can download Libre Office. It is a free office suite similar to Microsoft Office. Libre Office should be able to read most of Microsoft Office files, but the formatting could be off. However it is still usable. The download file for the whole suite is big, by the way, so you will need a good internet connection and it might take a long time to download.
Libre Office home page: http://www.libreoffice.org/
Libre Office download page: http://www.libreoffice.org/download
You can also create a Google account and use Google Drive (or formally known as Google Docs). Drive is a very limited Office Suite, but it will accomplish basic tasks and the great thing is that all your documents are stored on the cloud so you can access them anywhere with an internet connection. You can even upload your current Microsoft files or Libre Office files and have it stored in Drive or converted to a Drive document and view it there.
www.drive.google.com
You can create a Microsoft/Skydrive account and use their web version of Word, Excel, PowerPoint and OneNote. It has some limited features to the full fledge desktop application, but it might help you. Skydrive is also a cloud storage, so your files can be accessed with an internet connection. You can also upload Microsoft files to store in your account or view them. I do not know how well it works with Libre Office files.
www.skydrive.live.com
All of these options are free. There may be other options on the web that you may like, but these are are what I use since I do not have Microsoft Office installed on my home computer.
If your problem is just viewing Powerpoints instead of editing them, Microsoft does provide Viewers that let you read the files, but not anything else. Here is a link to download PowerPoint Viewer 2007: http://www.microsoft.com/en-us/download/details.aspx?id=6
If you feel you really need to have Microsoft Office, since you are a college student you can buy a lot of software (including Office) at a discount. You can look online or ask your college's bookstore or computer store or classmates about buying software with student discounts.