Power Pivot - links to excel files as source not recognized

Hello,
I have to use some excel files as sources for a Power Pivot
I can't connect to the excel files. The files are already tested on another computer and they work
The error message is (more or less)

the provider information are not included in the connection string. Please add them and retry

I report the message in Italian

Impossibile connettersi al server. Motivo: Informazioni sul provider non incluse nella stringa di connessione. Aggiungerle e riprovare. Se si tenta di effettuare la connessione utilizzando un provider gestito, scegliere l'origine dati appropriata nella pagina di selezione dell'origine dati, quindi fare clic su Avanzate per selezionare il provider gestito appropriato.

In the advanced connection string info I also can see:

Unable to get provider information. Reason:Unable to find the requested .Net Framework Data Provider. It may not be installed.

What should I do to solve this?
Thanks

Thank you CK76 I appreciate
I will check and give you a feedback

And here below another screenshot, which could be the explanation. OLEDB provider for Excel seems to be missing (bullet 2 of your answer) I find only the MS Access OLEDB provider

Missing data provider.PNG

I think installing the provider should solve the problem, at least it's worth a try before reinstalling the 4.5 Net framework

FYI - When you query workbook through Get & Transform (PQ) you should see Provider=Microsoft.Mashup.OleDb.1; in connection string.
This is the provider used by PQ.
0.JPG