Find items on your Depot
If your depot is unorganized you may lose items from time to time. In order to find items in your depot, you can use the Market. Simply search the market for the item you are looking for, put a sell offer up and cancel that offer immediately. It will be placed in your inbox.
This only works for premium players and it does not work for items that don't appear on the market (e.g. writable items or items that disappear over time). It also costs a fee (1% of the offer's value or 1,000 gold maximum). Another issue is that another player can buy your item before you cancel it, so it is recommended you set your offer for more than the item is worth.
You can also use this method to sort your items. If you have for example 5 backpacks of avalanche runes (10000) in many places in your depot, you can put all the runes up for an offer, cancel it and all 10000 will be in your inbox, perfectly stacked. Or if you have a huge backpack of loot and want to sort by buying NPC, you can do it by putting each item an NPC buys up for sale. Just take into account the fee to use this method.