maxima ignition

If you're lucky, there is a sticker in the glove compartment that has the key code (unless you removed it & put it in a safe place). Nissan can make a replacement key from that code.

The set of keys for the car came with a tag with the same code number, that could be used.

If it's a newer model, the dealer may have the key code in their records. You'll need to bring proof of ownership, VIN, & ID.

If you have no luck there, the locks can be replaced, I've only done it on sentras, they are about $170 for the set and then labor (I did mine myself)

Gary K