You can try teasing your hair. You can use a comb, or a bristle brush, and vigorously brush against thr growth of your hair at the roots to add volume. You can also blowdry or flat iron the roots by pulling your hair torwards the ceiling as you applying th heat to give it some lift.
To add volume to flat hair, you could use the "teasing" technique. To tease your hair, get a comb and take sections of your hair and comb upwards instead of downwards, then brush it out slightly. You can also use volumizing sprays, shampoos and conditioners to help with flat hair.
There are plenty of hair care products ranging from mousses to shampoos that fix the problem of flat hair. You can also use a curling iron or a flat iron to add volume.
Limp hair is everyone's nightmare. There are many reason why this may happen. One is putting too much product in your hair which will make your hair heavy, and make it flat. Another reason is genetics. Your hair may be way thin. To help is to use a hair volumizer.