This just means that you can only include letters and numbers in the field (and no special characters like ! or %). I’m assuming this is for a username you’re creating.
Register Hereor login if you are already a member
To list all combinations would take forever to type in. If you are forced to enter a number to meet their requirements you may just have to keep trying until it gets accepted. Examples: JohnSmith1, JohnSmith2, JohnSmith3, JohnSmith4JohnSmith5, JohnSmith6, JohnSmith7, JohnSmith8JohnSmith9, JohnSmith10, JohnSmith11, JohnSmith12JohnSmith13, JohnSmith14, JohnSmith15....
Some sites will may make a suggestion if your name ID has already been used. Like JohnSmith23456, JohnSmith784, JohnSmith95126. It's just the name and a random number that has not been used to create an account.
If you are getting an error creating the account, could you post the error message and if it's a website we would have access to the web address and we can see what the problem may be.
If I were you, I would try
@kelliekuhnie13, alphanumeric means, either you put your username as letters like A-Z or a-z or numbers like 0-9 with mixed mode. Check that website asks for either special characters like @, _ etc. You can follow their suggestion which can be found on their website. But be careful while sharing your personal details, if any.
@Safwan2571991, more information is needed to get help. Where did you want to write this name? Is it an email account creation ? Or something other?
@SHASHIKOTIYAN, please read all discussions minutely, & take a look links also. You can easily get good help. No need to repeat same replies again.