Since I modified a wrong buffer size or something in the settings of 0.43.4,I can't open pd again! I find there is a help doc on official website, but it doesn't work. Following the help, I deleted the org.puredata.xxx which is the statement of pd for system, but it stills stocked on startup.

Then, I try to replace the content files of 0.43.4 by the files of 0.42.5 ,and I found that the problem is from the "Resources" folder. But then,sadly, I have nothing to do.

I trying to modify the buffer size is because IAC midi signal is not stable.Now, I only wish to open it....

So, is there any method to restore or initialize pd settings? Please help me!!!Thanks guys!!!

I got a new clue. I found that if I delete the file "AppMain.tcl" which is in the "Resources" folder, pd can be opened as a blank,without any interface or function. And then I found the "AppMain.tcl" is opened by an application named "Wish".So I think the problem is from some pd statement in the files of "Wish". Then, I don't know what to do.Please help me,thank you!!!!!

Maybe try to reinstall it....
Check the mailing list archives, there must be something there about the Wish.app. Or maybe it's some .conf sine of Pd that I can't remember of. But there must be a file somewhere where you can tweek things.
Try installing the latest vanilla from Miller's website and then install the deken plugin from GitHub so you can install the externals you want. Anyway this is what Pd is becoming since extended is no longer developed.

Try loading pd with the "-noprefs" startup flag. If that doesn't work, then look through this list and see if there are any other startup flags that might help:

https://puredata.info/docs/faq/commandline

@alexandros thank you very much! I feel like fishing for a needle in the ocean. I'll try to forget the 0.43.0......

@LiamG thank you very much!But I can't open it normally,so I don't know how to load "-noprefs".But still, thank you a lot.

You can use the command line for startup flags. If you're on linux, open the terminal (ctrl + alt + t) and run:

      pd-extended -noprefs

@LiamG Thanks! So how to do it in mac?Deeply appreciate!

@Heisenberg I would definitely try the -noaudio flag That should get Pd started and then you can try to set your audio settings again.
David.

@whale-av thank you a lot! Do you know how to set the flag by Mac Terminal rather than pd?Because I can't open pd to set the flag......thank you!

@Heisenberg I've never really used Macs, but there must be a Terminal application somewhere. Google says it is in the Utilities folder.

@LiamG Oh! You reminds me! Thanks you!!!!!!!

@LiamG Sorry about my grammar........

It's in Applications/Utilities/Terminal.app
In there type /Applications/Pd-extended.app/Contents/Resources/bin/pd -noprefs -noaudio
Or use any flag you want. Note that in the Terminal you can type a few letters and then hit the tab key. For example, if you type /Appl and hit tab, the Terminal will complete the word Applications for you. This is less error prone will using the terminal.