I am a grown man and I am crying right now because I lost my little kitty at Costco, I have no fucking idea what to do.
Hey I just saw this. I just want to let you know to keep up the hope. I was in a similar situation a couple of years ago. I lost my male cat (he was practically my best friend). He got out one night in April and since he's an indoor cat he had no way of knowing how to get back in. I didn't notice until the next morning. He must have gotten out when my dad was having a cigarette outside. I panicked and immediately went out searching the neighborhood. I couldn't find him. I continuously searched for him every single day. There would be times where I would see him but I couldn't get him to come. I would leave food out every night, but only seemed to attract strays, skunks, and raccoons. I put up posters. I replied to ads saying they found a cat that fit my cat's description. I told neighbors and friends in the area. Nothing worked. This process repeated, literally, for 8 months.
Fast forward to December. At this point, I had pretty much given up hope that I would ever see my cat again. I still thought about him every day but it just wasn't realistic that I would see him again. One day, I went and got the mail. Our mailbox is at a central location, so I have to walk about a block to get there. I kept noticing an abnormal amount of dead rodents on the way there. I thought it was strange but didn't think too much of it.
A couple of days later, I went out my back door one day. I saw a dead mouse on the doorstep. I immediately thought of my cat and couldn't help but think he was sending me a message. Sometime shortly after, I went looked out my back window as I frequently did just thinking I would see my cat waiting for me. I thought I saw something so I went outside. Sure enough, there was a cat. It was very late at night and it didn't resemble my cat, but I was still curious. As I got closer and closer to the cat, I realized it was my cat. I calmly tried to get the cat to come to me using treats as a lure. It was a tedious process that took nearly a half hour. He was famished. He looked like he hadn't eaten in days. He was apprehensive and protective as cats naturally are but he couldn't resist the food. I finally got close enough to him and I just grabbed him as fast as I could and I ran in the house. Under the light, I was now 100% certain it was my cat. I was so relieved and upset at the same time. I couldn't believe I was reacquainted with my beloved cat but he was in such terrible shape it was unbelievable. I could lift the cat with only a few fingers. He immediately walked around like he had never left and went right to where we fed him expecting to find food. I spent hours just hanging out with him and comforting him. He seemed to be fine mentally, but physically he was exhausted and was in rough shape.
He has since made a full recovery and has had very little interest of going outside. This is years after the fact but sometimes I still am amazed that I actually found him. Like I can't believe he's here. I can't believe he survived. I live in New England and during that time we had a hurricane and a blizzard. The weather was miserable, overall. Aside from that, there were tales of coyotes in the area. It was unbelievable.
I realize this is a very long post but I just wanted to give you some encouragement. Never give up hope. I tried for months and when it seemed to me like all hope was lost everything turned out ok. If you have any questions or anything let me know. I know it sucks. Good luck.
TLDR: Keep your head up and never give up hope!
PS: Sorry I can't figure out the formatting so it's just a big wall of text.