As my 97 camry was going down the road, it just stopped running, checked alternator was bad replaced, still not starting, any idea?

Borrow or buy a code reader and see if you have any stored codes.

If it died without any warning, it may be a broken timing belt. You have to find out it you have spark and gas. Whichever is missing or weak, you have to investigate further.

4- or 6-cylinder engine? It appears the '97 4-bangers have dual ignition coils...one serving cylinders 1 & 4, one for 2 & 3. Unlikely that both died at the same time, but one dying would probably prevent starting. 6-cyls had separate coil-on-plug.

Other thoughts might be a blown EFI fuse or the aforementioned broken timing belt.

Just curious but if the engine stopped and you could not re-start how did you determine the alternator was bad? I would assume you may have taken it off and had it bench tested but why did you select that part as the begining point to track down a "sudden death" and starting problem?