The Ego
Dreaming of losing your bag: meaning and interpretation
What you carry to be yourself
Identity, resources and security: keys, papers, money, everything that lets you move through the world.
Symbolic reading
Losing your bag or backpack in a dream, or having it stolen, tends to come in times of change or exhaustion, when you feel that something holding you up is slipping away: your role, your security, your sense of who you are. Notice what you missed most while searching. Documents speak of identity, keys of access, the phone of connection. If you got it back, your resources are still there even when you cannot see them.
Jungian key
In Jungian terms, the bag is a container of the ego: it holds what the ego needs to find its way in the world. Losing it leaves the ego without its usual supports, and that, frightening as it is, opens the question of who you are when you are carrying nothing.
Check what you really need to carry. What matters most usually weighs less than you think.