Same account, same region, so this cannot be the problem.
Friend was using my account on his phone to help me progress and get more cards. He also bought a couple of packs and he built a bunch of customized decks. However, when logging onto my (the same) account on my phone, none of this shows.
Help!
As all account data is stored on the Hearthstone servers, it isn’t possible to lose your progress. You’re either using the wrong Battle.net Account or you’ve logged into the wrong region.
Double check you’re using the exact same email on all devices.
In the Blizzard Launcher, check all three regions by adjusting the dropdown menu above the Play button.
On mobile devices, log out then change your region using the drop down in the top right of the screen.
The CMs in the Tech Support forum can give hints as to which region/account has the most progress, or you can submit a Support Ticket asking about your account;
https://us.battle.net/support/en/help/product/hearthstone/1398/1422/channels
It’s illegal to let people use your account. So the bigger problem I’d be worried about is getting your account banned for admitting account sharing.
One of these statements is wrong. Check twice.