Unvailable files after restoration of a Teams team

I work in a enginner school and I'm in charge of deploying Teams.

I accidentally deleted a team that my administrator restored a few days later however the students lost their files that were in the different private channels of this team. 

I don't know if it's related but in fact this team had been badly configured at its creation, it was of "Personal" type whereas I wanted it of "class" type to have the tabs "homework" and "notes".

So I deleted that team and after I recreated one with the same name.

On Sharepoint I also don't have anything, I looked in the trash and the second one but everything is empty. I tell myself that if I get this error message it's because the files probably still exist but are no longer accessible.

In conclusion I did this in this order :

1) My admin create a "staff" team with a few private channels with and files inside them

2) I create a "class" team with the same name

3) I deleted the first team

4) My admin restored it but files didn't reappeared

Thank you in advance because my students are in a bad way, these documents are important to them 😕