try to run some programs -a warning that ''the entry point is missing '' so how to fix this one?

Have you checked for infections? If not, get the Anti-Malware Toolkit. Since you're on XP you'll also want to try Dial-a-fix. The more information we get from you, the better we can assist in resolving the issue. You should also run sfc /scannow.

i did sfc sorry no help ...mscrt.dll is not showing file name but still the program is still working !

What programs are giving the error?

Sounds like you have mismatched versions of a .dll runtime, and an application is calling an entry point into that .dll that it expects to exist, but doesn't. A couple of questions:

1. When did this start?
   
2. What changed (if anything) at or around that time on the system?
   
3. Does this happen to all applications, some, or just one or two?
   
4. Does the error, if it happens frequently, list the entry point that is missing, and in which .dll?
   

Sounds like you have mismatched versions of a .dll runtime, and an application is calling an entry point into that .dll that it expects to exist, but doesn't. A couple of questions:

1. When did this start?
   
2. What changed (if anything) at or around that time on the system?
   
3. Does this happen to all applications, some, or just one or two?
   
4. Does the error, if it happens frequently, list the entry point that is missing, and in which .dll?
   

all is well ! with that one some old files not used cause this troubles !