If they hosted Limesurvey, they are responsible for the data. As long as they did not host it with the Limesurvey GmbH, which I doubt, they are the only ones to provide you with the data, because it was stored on their servers and their databases.
It is ridiciulous to stop hosting without giving people the chance to export their surveys and their data. I would complain with the IT department or even with the dean of the university. It is one thing to decide to stop hosting. This is their decision. But you can't just stop hosting a service that students / professors depend on and not even giving a warning.
Now, you might not like it, but I have little hope, given what they told you. They tried to blame someone else for their mistakes (you are probably not the only one in this situation, if they did not give a warning) and I fear they do not have a backup and probably have deleted the database. If this is the case, there is no way you can get your data back. I hope you have a least a fairly recent backup of your data somewhere. But I fear that everything collected in between is probably lost.
But I would really escalate this to a higher level, because this is just ridiculous behaviour. At least give the chance to export the data within a reasonable timeframe. As it is a US university, I assume you pay good tuition money and you can expect a far better service than that.
If you are lucky the database is still there. However, I doubt that they will extract only your data from this database and I also doubt that they will give you a dump of the whole database.
Help us to help you!
Provide your LS version and where it is installed (own server, uni/employer, SaaS hosting, etc.).
Always provide a LSS file (not LSQ or LSG).
Note: I answer at this forum in my spare time, I'm not a LimeSurvey GmbH employee.