lost connection power pivot table

Hello,
Sometimes i loose my connection to my query on my pivot table? Does it have anything to do with "adding to data model" choice i've made? How can i rebuild my connection with loosing my pivot table?
Tks in advance
Pedro

Go to Design > Existing Connections
Under Workbook Connections select the Power Query (in this workbook, Power Query – Macro photography lenses)
Click Open
Copy the Connection String
Then click Cancel, we don’t want to re-import that table again.
I think this is where the magic happens. If I’m thinking this correctly, when I changed the Power Query, I changed the connection string, so this is a copy of the new (corrected) connection string.
Then go back to Design > Existing Connections
Now we go under PowerPivot Data Connections and select our broken Power Query connection, and then click Edit
In the Edit Connection dialog window, delete the old connection string and paste in the new connection string.
When you’re done a message will appear in the bottom dialog, click Save.
Close the Existing Connections Window
Go back to Home > Refresh

And
Go to Design > Table Properties
“Closest Focus” is not checked, just check it.
Click Save

Also please check this link if you want more informations about this problem. http://exceleratorbi.com.au/solved-p...lt-0x80020009/

Hello Amanda
First of all, thanks a lot for your answer.
In my excel version, there's no "existing connections under Design, but under Data, there is Connections.
The problem is that i have like 9 data sources to choose from and don't know which one.
But let me ask you something: should i do this pivot table adding to data model?
Don't understand much how it is for the data model, except for big data. Do you know any video that explains how data model works?
Tks again
Best regards
Pedro