Reset or assign customer a new Password manually?

I have a customer...he lost his password.
He clicks the "Forgot your password" link and then enters his email address
No email arrives. He claims its not in his spam folder either.
I repeat the process for him, he claims the email never arrives.
I put in my email address, and I get my new password in about 5 seconds

How can I manual assign him a new password?

Under TOOLS menu, try first sending that customer an email. This will test the capacity of your system to send him an email. Get him on the phone while you do this, so you can see if he receives THAT email. If he get that message, then there should be no reason why he does not get his password reminder.

Perhaps look ALSO in his Customer Details record, It will show you what email address he used when signing up. Is it correct? (ask him).

Another way is to temporarily change HIS email address to another that you could set up on your own C-Panel. Then do a password re-set using the conventional method, using the NEW email address. It will be sent to "you".

When you have reset the password, change that email address to his original address.

Or, you could ask him to set up a quick address at hotmail, you put this into his customer record, and he then resets using that new password.