my skin does not appear in single player or multiplayer

my minecraft launcher does not show my skin on singleplayer or multiplayer on version 1.7.5 - 1.12.2
but my friend noticed that I was wearing skin while playing multiplayer server.
please help me solve this problem.
I've tried to change from minecraft.net repeatedly, from the launcher is repeated, but still does not bring up my skin. just bring up the default steve skin