Report It Immediately
Contact USCIS as soon as lost. File I-90 (Application to Replace Permanent Resident Card). Fee: $455 + $85 biometric. Processing: 7-10 months.
Can You Travel Without It
No. Without Green Card, you can't reenter US after leaving. Get replacement before traveling. Expedited processing available ($1,140 total).
What You Need
Filled I-90 form, copy of lost card (if you have photo), two photos, state ID. Biometric appointment required (fingerprints).