Why didn't he get a raise?

All of this may be totally in line with their pay schedule. If husband took a new job - not likely he would get the same pay as the one who quit - until he proved he could do the job. And the other guy getting a raise may be getting that due to being there longer and it was time for his raise - where it isn't time for your husband's. Many companies give raises to all once a year. Or on employee's annual anniversary. Neither of these may apply to your husband right now.

He can certainly talk to his supervisor about it - which is never a good idea. What other employees make is none of the rest of the employee's business - and companies don't much like when one complains about someone else getting a raise - when likely the complainer does not know all the facts - such as timing of raises for anniversaries and such.

A lot of giving raises depends on length of employment, various duties and such.

So just because one got a raise does not make another "entitled" to one.

Your husband would need to talk to either his boss at Walmart, or the HR department about this.

I recommend you go back to school and learn about grammar, punctuation, and spelling, or neither of you will ever have a job better than Walmart.