Losing a child can mean two different things. In the case that a parent lost a child when running errands, you can tell them that you are going to help them find the child or will call the police to help them out. But, if the parents lost the child in an accident or unexpected death, you can offer your love and support. You can even try and ask the parents what happened, if they are comfortable speaking about it, so you can say more helpful phrases to them.
I'm so sad to hear about your loss
(child's name) will be missed by many
(child's name) was truly a wonderful person
I wish I could take away your pain
If there's anything I can do to help, please let me know
(child's name) was such a shining light in so many people's lives
(child's name) will be in our thoughts and prayers
(child's name) was such a generous person
We all miss (child's name)
I wish I had the right words, just know I care
I don’t know how you feel, but I am here to help in any way I can
I am always just a phone call away
We all need help at times like this, I am here for you
There is a reason for everything
I wish you nothing but comfort and strength
I extend my deepest condolences to you during this dark time
I hope that the love and support from your family and friends, including me, gets you through this time
If you need anything, know that you’re not alone. I’m here for you
While there’s nothing I can do to change what happened, I can continue to offer you my love and support
Extending my most heartfelt condolences to you and your family
You have my deepest, sincerest sympathy
I am praying for you during this dark time
My sympathy is with you in your time of grieving
Cheer up. (child's name) wouldn’t want you to be sad
(child's name) is in a better place
May all the sweet memories of (child's name) bring you solace during this time
I hope and pray that you will have strength during this time of loss