How long for a viral syndrome to go away? severe tension headache,fever,tiredness,restlessness,sore throat severe,congestion,minor body aches

Sounds awful: Everyone is different, and these nonspecific viral syndromes vary a lot. If it's just a pharyngitis (sore throat) those usually improve within 3-5 days, but mono would be a situation where a sore throat lasts a lot longer. If it evolves into a cough or something more flu-like, that can hang on for weeks (though the fever/achy stuff passes after the first few days). Sinus stuff hangs on too.