There are few projects for which i applied , its been 15 days the client is not hiring someone nor seeing the post, in that case my bid is wasted, is there any thing i can do ??
No, nothing you can do.
You've done your best (you've sent quality, comprehensive, job related proposal).
If the client doesn't contact you, your bid is 'wasted' (you've gained experience, so it's kinda NOT wasted).
Clients may post on several different platforms; clients may decide to use their own people or someone local to do the job; clients may decided the job is not necessary; clients may decided they don't have the budget to hire for the job.
This is part of the whole process of running your own company. Be cautious and careful about the jobs you submit for and then just move on.