My ex-wife left me for a deaf man. To be honest, I should have seen the signs.
Anyway, finding lost stuff is pretty easy.
Is there anyone else that could have moved them?
Is there anywhere else in the house you have worn / had them? You may think they are in the bedroom, but are they..?
Is there anything they could have fallen behind?
Is there anything that may have covered them? A pair of stray underpants or a sweaty t-shirt?
Are you looking straight at it but not seeing it?
Has it become displaced, for example become moved to the back of a drawer when you've looked for something else?
The most important thing is to look once, and look well. Unless you're like Mr Trebus then you should be able to search slowly and methodically - don't make the mistake of doing a half-arsed search. Split the room into zones and look properly and carefully until you are sure you can tick the zone off.
If all else fails, have a cup of coffee and chill out. You'll remember where they are in about 3 hours time.