[ball]

You have to checking in OnPlayerDisconnect callback if player is muted or is in jail. Create for this new table (for example jailedplayers) and in OnPlayerConnect and execute mysql query

Code:

//OnPlayerDisconnect
if(jail || muted) //i dont know name of yours gamemod variables
{
mysql_query(INSERT INTO ...); //save player name, uID (if your gamemod have uIDs for registered players, time)
}

//OnPlayerConnect
format(string, 128, "SELECT name, uid, time from jailedplayers where uid = %d or name = '%s'", ...);
mysql_query(string);

if(mysql_num_rows()) //system found something
{
SendClientMessage(playerid, -1, "You has left the server while in jail or you was muted!");
//the rest of code
}

Of cours this is only a clue for this.