Product has 0 weight ...

Checkout shows no Shipping Modules ...

Does 0 weight mean Free Shipping? If so, install Free Shipping freeshipper Shipping Module ...

If 0 weight does not mean Free Shipping, change the setting in Shipping/Packaging:
Order Free Shipping 0 Weight Status
If there is no weight to the order, does the order have Free Shipping?
0= no
1= yes

Note: When using Free Shipping, Enable the Free Shipping Module this will only show when shipping is free.
NOTE: Check if you have Zones set on your Shipping Modules that you have covered all Zones so that people can checkout ...