Its telling me my phone doesnt have enough memory to send texts and says my message memory is full even though i have erased all messages? I baught a 4gb memory card hoping this would solve the problem but it hasnt made any difference?

hey its easy,
first install the app "app2sd"
then check the available space in device
if it is below 20 mb u cant recieve messages
for solving this problem uninstall some apps installed in phone memory....

Go to messages

Then text messages

Then to options

Then SIM Messages

Then delete the SIM Messages.

The memory after deleting sim messages is empty,and you dont need to delete any application

no you didnt erase the all messages yet
you just erased the messages in your phone only
but there are messages still in the sim card
go to messages the options the simcard messages then they will appear so now you can erase them
an the memory is empty

Go your message setting. There is option where you'll save your message and choose save to memory card.
Delete all message in inbox and outbox folder, delete all cache in your browser and close all active applications. Try to send text message.
If the notification "Memory full" still appear you must uninstall a one or more application (not just close it but uninstall it) to make some space in your phone memory. Choose application that you don't use the most.
If the problem persist, format your phone back to factory setting.

Hope this help and if helpful RATE please.

all because it is programmmed that all msgs should remain permanently in inbox except it is been flash to put in new memory.

Pictures, saved music or files and games. I believe.

you inbox, outbox, and draft box is all empty???

Unfortunatly you have to call your cell carrier to RTN your phone which will erase everything in your phone. You may try to go to a store to get a software update.
FYI. I worked for Sprint for 3 years.

DELETE YOUR COOKIES AND TEMP INTERNET FILES

menu->messaging->settings->All msg->turn on auto erase->ok->turn it off and it should work