I have a front crown and had so for around 8 years, it's become wobbly. (Photo)

It all depends on what's loose & if anything is broken. It is not possible to diagnose without an exam & xray. there are so many different possible scenarios:
Best case scenario: the crown is loose, no damage to the tooth underneath, no new cavities, crown is in a good shape. the dentist can just cemented it.
It also could involve different type of fracture,from the crown to tooth, above the gum line, below the gum line, the whole root. Worst case scenario: the tooth needs to be removed. You need to see a dentist to avoid further damage.