My daughter age 15 suffering from b12 deficiency. please suggest injections for her?

See details: She needs vitamin B12 injections which are usually given monthly. This issue needs to be addressed to your daughter's physician.

? How diagnosed ?: This is not a common diagnosis in a teen. If true, the physician who found it would also look for a cause that may have other health ramifications. When the origin is clarified a plan of treatment including B12 would be appropriate. You don't begin treatment without exploring why the problem exists.