How to recover deleted photos and videos from Trash on iPhone?

I'll guess that your pictures and videos were in the Photos. If they were in another app, then that would be another story. As Matti Haveri says, you don't give us information. So I guess this is the longer answer:

When we choose to trash a picture, we get this:

If we choose to defeat this safety, then when we select pictures to remove them from "Recently Deleted," we get this warning before the final step:

So we have to choose delete four times (from Library, from that warning, from Recently Deleted, and then from its warning.) There is no 5th safety. If we use iCloud Photos, then that "synchronizes" its Photos Library with the phone, so what we see on the phone is what is at iCloud. iCloud Photos doesn't keep pictures in "Recently Deleted" any longer than the phone does

You can see this:

        If you're missing photos or videos in the Photos app

Basically the above says to look in Recently Deleted and in Hidden. Be sure to check your Library thoroughly. You can use the search field with the date or location—the pictures may not be where you expect, as dates may have changed. And remember, you can sort the Library by date captured or by date added. Also, your Library view now has filters, and you may not have your filter set to "All Items.”

If you don't use iCloud Photos, but you have Settings>Apple ID>iCloud Backup turned on, then you may be able to recover data. You should look here:

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support 

“Restore” is what you do when you buy a new phone, so this safety, if you have it set, requires you to erase everything on your phone and replace it with the backup. You would have to get to the backup quickly, usually within a day, before the backup is replaced by a newer one. However, if you did have iCloud Photos enabled, then the iCloud Backup wouldn't make an extra copy.

Perhaps you have shared your pictures with friends-- then you could get them to send copies back to you.

Unfortunately, if you don't keep your own backups to an external drive, then there really isn't any place else to look. To back up your pictures you can just plug in an external drive, select the pictures, and use Share>Save to Files. Alternatively, you can backup to a computer:

Transfer photos and videos from your iPhone or iPad to your Mac or PC

If you haven't done one of those backups, then your remaining pictures continue to be in peril. 

Restore from a backup. You don't say if iCloud Photos was enabled or not -- that info might produce a longer answer.