Get rid of the crickets right away, please. Garter snakes will not eat crickets, but the crickets can attack the poor snake.
Do you have the ability to post a photo??
The 2 best things to try are small earthworms, I cut them in half. (if you dampen a old hunk of cloth and lay it in your yard for a day or two, there will be some tiny little earthworms under it, or if available any debris or big flat rocks already there could yield a small worm or two.
The other is try placing some small guppies in with the snake.
Some (most) of my babies will respond to the little fish right off, others respond to the worms, then give them a small fish right away, once they start feeding they tend to want more.
Teasing the snake by jiggling food in front of its face with tongs/tweezers/hemostats will often trigger a feeding response.
Good luck, and keep us posted please 

Dances With Reptiles
-----
Regards,
Wayne A. Harvey

1.0.0 Ball Python - Python regius "Cane" Rescue
0.1.9 Eastern MilkSnake WC "Carmella" adult super sweet temperment (Eggs all hatched!)
1.3.13 Storeria dekayi Casper, Xena, Athena, Sharon & Kids
2.1.0 Thamnophis sirtalis - eastern Garters
0.0.1 Thamnophis HybridAlbino Checkered Normal eastern
2.0.0 Thamnophis sirtalis - eastern Garters (xtreme orange phase)
1.1.0 Thamnophis RADIX - Snow Hets
0.1.0 Thamnophis RADIX - Christmas Albino
0.0.1 Thamnophis sirtalis - Red Phase Eastern Garter red and white stripes
0.0.1 Thamnophis butleriButler's Garter Snake
0.0.4 Thamnophis proximus orariusCoastal Ribbons
0.0.16 Thamnophis sirtalis - newborn Eastern Garter babies 7/11/08
0.0.17 Thamnophis sirtalis parietalis HET Anerythristic Scott Felzer stock.
0.1.0 Thamnophis sirtalis Eastern Snow "Snowflake"
0.0.1 Thamnophis sirtalis infernalis California Red Sided (R.I.P. little guy)
1.2.0 Thamnophis pickeringi - Puget Sound Garter "Sky" (adult, Sky blue) 2 females recently aquired.
0.0.1 Nerodia sipedon - Water Snake - "Aqua" adult WC
0.1.0 Storeria occipitomaculata - Red Belly snake (Her children were raised & released)
0.0.1 Amelanistic Corn Snake "CY" Sub-adult CB
1.0.0. Pueblan Milk snake "Oreo" adult CB
1.0.0. ASIAN GREEN SNAKE 3' WC Cyclophiops major"Limon"
0.0.1. Savannah Monitor "CHOMPER" Growing fast!
1.1.3. Green Anole "Crystal" & "Chris" WC dropping eggs fast!
1.0.0. K9 "ACE" Black Cockapoo
0.2.0. Feline"Felix"(R.I.P. 4/27/08) "Kaja" & "Silver"
2.1.0. calico RATS
2.4.?? Mice - Feeder farm - Crickets / fish
More herps than I could ever list out back on the land. 
