Hello RubenGonzales88
Thanks for contacting us. Sorry to hear you have misplaced your pen.
To attempt to locate your Surface Pen, you can view the last location it was used on your device by going to Settings > Update & Security > Find my device. In the Where's my pen? section, select Go here to track it.
If you are unsuccessful in finding your pen and would like to purchase another one, you can visit your local retailer or Store to get a replacement.
Best regards