I work as a CST for a living, so here is what I suggest.
1. Even though you have office on a mac, you'll still could have issues retrieving the files, as the MAC operating system is different. To break this down into even simpler terms, a PC runs Windows, and an Apple computer runs Mac unless you have Windows installed on a Mack, which can be done to new Mac computers since PC's and Macs are now using the same processing chips. If you'd like, you could take your computer to a shop and ask that they partician your hard drive. Not to confuse you, this means that you could have both operating systems on it, and you can choose to boot into one or the other. For example, when your Mac would boot up, a screen will appear that will enable you to choose whether you want to boot into Windows or the Mac operating system.
2. Get to a PC, and you should be able to retrieve your files from the memory stick. If you still can't retrieve them, this could mean one of two things. 1. You never saved them and think that you did, which sometime happens to the best of us. Or 2. The memory stick went bad. But, don't lose hope, as there is still something else you could do.
3. If you still have your old computer, take out the hard drive, go to a computer shop, and have them retrieve all the data off the system's hard drive. Or, you could have an external hard drive made out of your old hard drive meaning that it can be turned into a storage device just the same as your memory stick, but it will have way more data space, as well as an operating system. If you don't know where your hard drive is, take the computer to the shop, and they'll be happy to do this for you.
I hope I was of some help. If you have any further questions, don't hesitate to ask.