https://citizenpath.com/lost-green-card-abroad/

Something similar happened to me while in Europe. I had the GC with me, and crossed the security check in. Then, I lost the GC inside the airport. So, when I was getting ready to board the plane, I realized, I do not have the GC anymore. I informed the airline employee about what happened. Apparently, in Europe, the US government people are in the airport always, so a guy representing the Federal government of the US came to the gate within 15 minutes. He asked for my A number. To verify my identity, he asked his coworker in Washington to text him the picture and details of that A number. He got a text with my picture and details, which matched with my state ID. So, he asked the airline employee to let me board the plane, and I did not miss the flight.

May be, something similar happens in Nepal too. I am guessing the whole embassy can't take a day off without an emergency-handler. So, you might want to ask your friend to get in touch with the airlines or look for emergency US embassy line.

And how about the in US ..Did they let u in without any problem

There was around $400ish fine for "traveling abroad without the GC by a US permanent resident." The guy at the Europe airport told me to be ready to pay that fine once I land in the US. However, I was not asked for any fee at the US airport. So, I guess, the fine depends on the customs officer's discretion. I was taken in to the secondary screening for additional questions at the airport. They were mainly asking questions as if I was an asylee who has "illegally gone to Nepal and returned from Nepal." When they figured that was not the case, they let me go with information about how to get a replacement GC. I did not have to do that, because my card was later found at the Europe airport and mailed to my address.

u need to make police report

Bro. You have to go to US Embassy in Maharajgunj. Thursday morning is the only day for Greencard holder issue. Basically you have to explain what happened. You will fill out all the papers. And then they will interview you. Ali gaali sunnu paryo. In my case, I had to wait for their call. Make sure to give them your cell number. If you dont get a call after a week, check with them again on Thursday morning. I got one month visa to get back.