I installed Oracle 10g express database for a SQL course i’m taking on my windows 7 computer. it worked perfectly fine for a few days after. Then, I didnt use the computer for about 4 days. I’m working on a new part of the course, and i realize that the program is no longer in its original downloaded form anymore. it shows up as Oracle_10g_XE, and no matter how many times i clean my system, install and uninstall it, it wont come back. im behind on my work. whats wrong with it pls help

Tried uninstalling and installing, cleaning it out, etc, cant figure out why it suddenly stopped working on the very same computer, or if i accidentally changed some permissions