CONFIGURE THESE SETUPS:
in your php.ini:
SMTP=smtp.gmail.com
smtp_port=587
sendmail_from = my-gmail-id@gmail.com
sendmail_path = ""C:xamppsendmailsendmail.exe" -t"
in your sendmail.ini
smtp_server=smtp.gmail.com
smtp_port=587
error_logfile=error.log
debug_logfile=debug.log
auth_username=my-gmail-id@gmail.com
auth_password=my-gmail-password
force_sender=my-gmail-id@gmail.com
Although there are portions of this answer that apply to only to the usage of themail() function itself, many of these troubleshooting steps can be applied to any PHP mailing system.
There are a variety of reasons your script appears to not be sending emails. It's difficult to diagnose these things unless there is an obvious syntax error. Without one you need to run through the checklist below to find any potential pitfalls you may be encountering.