When I want to save my file,it always say save failed,then I use save from..

This is an easy question to answer you simpily go to the save game option in filethen when you turn the game back on later go to load game a vioala you have your game back from where you saved it this is also useful for hard poke battles

You use no$gba and it will save the game sincerley howard hoppe

I had the same problem as this,
I could only save through the emulator and not in game, which prevented me from being able to use Wonder Mail, etc.
Anyway by messing around with settings and such, for a friking long while, I came to the conclusion that in order to save (in-game), before you start your first save you should go into the emulator options then to save type and change the save type to "flash" and then change the part that says "64k" by selecting "124k".

Unfortunately this only works on new data. And by that I mean even after changing these options, any data made before you change this option will still fail to save. In essence this solution is only a solution for save failures so you can use Wondermail, etc if your willing to start a new game.
This should (hopefully) work however if you're willing to start anew.

However,
I am not 100% that this on it's own will work for everyone. So if that doesn't work, do this in addition to changing the save type, etc. When you start the game (I'm not sure if this should be done before or after the first save, I think more likely after your first save but don't be afraid to try a different order if this doesn't work), Go to file on the emulator, select import then battery file and try to find a viable file. If you look around but can't find a suitable file do this instead: select export and then select battery. Having done this then select import and look for a file with the extension ".sa*" (The * should be a number).

It should give a warning about loss of data blah blah blah. Proceed anyway. Yeah The solution will only work if your willing to give up any previous data. But that should work if nothing else has.
I don't know a heap about emulators and such so I just played with options awhile. But These things are the only things I think that had any real result.
I hope this helps.

If you wanna know what other random settings I messed around with you can e-mail me if you want.
Msg me I guess? I dunno.

I'm sorry that this only works in saving new data :/ Gotta make a choice whether you can be bothered starting over I suppose.

But after I did this I could successfully save data with the emulator save option so I could access wonder mail, etc.