were could it have gone? it has vanished...

i have a gold lockett i wear on a chain arround my neck, it has been there for the last 2.5years, nezt to my grandmas wedding ring, i only ever take it off when i feel realy sick.
i woke up yesterday and as always adjusted my chain (as they get tangled from time to time) and only y ring was on the chain, the lockett was gone! i spent yesterday looking everywere for it, but nothing! the oddest bit is in all the time ive had it on it hasnt once come off, it is drivingme mad as it is the only jewlwery i wear as it means the most to me.
and ideas/thoughts on were it could have gone to would be much appreciated, thanks!

Could one of the kids pull it off by accident?
I guess it could be anywhere :(

when I lose jewelry it's usually in the bedroom, probably came off when you changed tops or had a shower etc. Also check the bathroom.... Goodluck

somewhere in your bed.. Even possibly in your pillowcase or under the mattress