Originally posted by knighttemplar1960:

Back up your save on your hard drive or a flash drive. If you get a cloud sync error you can go to Valheim in your steam library display and click on the cloud status icon to try to force a resync.

If you feel a game bug cheated you, you can use dev commands and spawn in all the items you lost.

knighttemplar1960's advice is very applicable to your situation. I have used the dev commands twice so far after losing items, and am of the opinion that the developers added them to help players who have lost items through no fault of their own. I lost a Draugr Fang Bow, after destroying an item stand holding the bow.