Is that possible a guy can examine throgh vagina that a girl had a sex before so many times or even she lost Verginity? Is there any way to find out.

No mileage meter. Some place value on an intact hymen, although some are born without or lose it in childhood through non sexual events.There is no "sign" one can see by looking at the goods, although active herpes or similar STD suggests at least one encounter.Since the average age of first intercourse runs in the teens for both genders, most should not expect it at 28.
No . Not likely. There does not seem "to be any way for a guy to find out". Perhaps you may want to find out why you think a guy needs to know "that"and why that might be important to you, to that guy and to your partners. Remember the 3 "C"s : Communications.Communications.Communications.!