[Aly]

Well you've setted two different tags:
(This one from register)

pawn Код:

INI_SetTag(file,"Player's Data");

and(This one is from onplayerdisconnect)

pawn Код:

INI_SetTag(file,"Player Data");

Does the accounts load?

Try like this:
Replace

pawn Код:

INI_SetTag(file,"Player's Data");

and

pawn Код:

INI_SetTag(file,"Player Data");

with

pawn Код:

INI_SetTag(file,"Data");

Replace

pawn Код:

public loadaccount_user(playerid, name[], value[])

with

pawn Код:

public loadaccount_Data(playerid, name[], value[])