I deleted my pictures by

Are you using the free version of Lightroom Mobile, or do you have an active Adobe subscription? If you have an active subscription, any images that you delete (by accident or design) are stored in the "Deleted" album for up to 60 days, and they can be restored from there. 

But if you are using the free version, I don't think that the "Deleted" album option exists (though I don't know for certain), in which case if you delete an image it's gone forever unless you have a phone backup which contains it.