from p in context.rPlayers  
join d in context.PlayersDescriptions on p.id_Player equals d.id_Player  
join c in context.PositionIndexes on p.id_Position equals c.id_Position  
join cn in context.PositionsNames on c.id_Position equals cn.id_Position  
where cn.pName == lb_Position.SelectedItem.Text 
select new { p.id_Player, p.Name, p.Surname};

                
var res = from p in EOdb.rPlayers
join d in EOdb.PlayersDescriptions on p.id_Player equals d.id_Player
join c in EOdb.PositionIndexes on p.id_Position equals c.id_Position
join cn in EOdb.PositionsNames on c.id_Position equals cn.id_Position
where cn.Region == "EN-en" && p.Disabled != true
select new { p.id_Player, p.Name, p.Surname, p.Pound, p.Height, p.caricature, cn.pName, p.BirthDate, d.Description };

foreach (int i in lb_Position.GetSelectedIndices())
{
    var _res = res.Where(cn => cn.pName == lb_Position.Items[i].Text);
//così mi applicherebbe solo l'ultima che legge...no???
} 

                var res = from p in EOdb.rPlayers
                          join d in EOdb.PlayersDescriptions on p.id_Player equals d.id_Player
                          join c in EOdb.PositionIndexes on p.id_Position equals c.id_Position
                          join cn in EOdb.PositionsNames on c.id_Position equals cn.id_Position
                          where cn.Region == "EN-en" && cn.pName == lb_Position.SelectedItem.Text && p.Disabled != true
                          select new { p.id_Player, p.Name, p.Surname, p.Pound, p.Height, p.caricature, cn.pName, p.BirthDate, d.Description };
                var _res = res;
                foreach (int i in lb_Position.GetSelectedIndices())
                {
                     _res = res.Where(cn => cn.pName == lb_Position.Items[i].Text);
                }