[ReneG]

Oh my, I see what I did wrong.
I had to put all the code after the else statement.

pawn Код:

if(!strcmp(cmdtext,"/restart",true))
    {
        if(!IsPlayerAdmin(playerid))
        {
            return SendClientMessage(playerid, Color_Red,"Only admins can use this command.");
        }
        new gmxdelay;
        if(sscanf(cmdtext,"d",gmxdelay))
        {
            return SendClientMessage(playerid, Color_Red,"Syntax: /restart <minutes>");
        }
        else
        {
            if(gmxdelay == 0)
            {
                return SendClientMessage(playerid, Color_Blue,"It must be at least one minute.");
            }
            SetTimer("Timer_Restart_Kick",gmxdelay*1000*60,false);
            new string[128];
            format(string,sizeof(string),"The server will restart in %d minutes.",gmxdelay);
            SendClientMessageToAll( Color_Blue,string);
        }
        return 1;
    }