"Do not cry because it is over, Smile because it happened." - Dr Seuss.
Coping with 'Loss' is something we all go through some or the other time in our lives. The loss of a loved one, the loss of wealth, the loss of health. Whatever the loss, no matter the magnitude or the impact - we all have experienced it and would continue to do so. Nothing in life is constant other than change!
How we cope with a particular loss is different for different people depending on the situation they face. When you loose an item or a thing, you ponder about it for sometime, try and remember where you may have lost it, tracing back the steps trying to find it and after awhile if unsuccessful you just move on.
However when you loose someone close to you, the feeling of loss is so intense that it hurts immensely. Coping with this loss can only happen over time and there is no right or wrong way to go about it. What is more important is to cope with it the healthy way. We all need time to grieve and this feeling of loss & sadness too shall pass by.
You need to acknowledge the pain and loss you feel and not fight it. The circle of life continues - be strong, express and share your feelings and move forward once you are comfortable to do so. For some it may be easy to move along and for others it may take longer time. If you are struggling to deal with such loss for a longer time which is affecting your way of life - you may consider seeing a therapist as it could be a complex case in dealing with your grief.
Support of family and close friends at this juncture is of immense help. In case you happen to know someone unable to cope with their grief, give them a shoulder to cry on, listen to them and not say 'such is life', 'move-on', 'get over it'! It takes time and only people who can empathize can actually help in more ways than you can imagine.
Take time, cherish what you have today, live and love in the moment and don't have regrets for tomorrow!