[NewerthRoleplay]

Adding to what Abagail said you should also indent because the final command shouldn't look like:

pawn Code:

CMD:sethp(playerid,params[]) 
{ 
    if(IsPlayerAdmin(playerid)) 
    { 
    new Float:Health; 
    new PID; 
    if(sscanf(params, "ud", PID, Health)) return SendClientMessage(playerid, -1, "USAGE: /sethp [playerid] [health]"); 
    if(!IsPlayerConnected(PID)) return SendClientMessage(playerid, -1, "Player is not connected"); 
    SetPlayerHealth(PID, Health); 
    } 
    else 
    { 
    SendClientMessage(playerid, -1, "You are not authorized to use this command!"); 
    } 
    return 1; 
}

It should look like this with the proper indentation and with abagail's adjustment:

pawn Code:

CMD:sethp(playerid,params[]) 
{ 
    if(IsPlayerAdmin(playerid)) 
    { 
        new Float:Health; 
        new PID; 
        if(sscanf(params, "ud", PID, Health)) return SendClientMessage(playerid, -1, "USAGE: /sethp [playerid] [health]"); 
        if(!IsPlayerConnected(PID)) return SendClientMessage(playerid, -1, "Player is not connected"); 
        SetPlayerHealth(PID, Health); 
    } 
    else SendClientMessage(playerid, -1, "You are not authorized to use this command!"); 
    return 1; 
}