I forgot to send mt Class X certificate(for date of birth )along with the form for SRM will my form rejected or not ?

Since your date of birth proof isn't present, so they will cancel your form.

However, you should call them at the following number to request them..

Admissions
Director (Admissions)

Address:
SRM University, SRM Nagar,
Kattankulathur - 603203
Kancheepuram District, Tamilnadu, INDIA.
Phone: +91-44-2745 2270 ,+91-44-2745 3788
Extn: 1451, 7004
Fax: +91-44-2745 3622
E-Mail: dir.admissions@srmuniv.ac.in
Information Centre: Ph: +91-44-2745 5715, +91-44-2745 3433