Translating unique values

I have a bunch of data, on one spreadsheet, Say 20 columns that I can’t tamper with. i have a set number of unique values, on another sheet I have those same unique values(store number) plus a bunch of extra ones i don’t need, but I need to grab unique information(phone numbers) from the sheet that has the extra store numbers and place them into the excel sheet I can’t tamper with. Is there a formula that could help? Even if I have to put all the info on a different sheet and filter them a certain way, i could do that.