This is one of those things; I accidentally deleted “Default Player” right in the middle of a project; movement is DEAD!. I am not sure but the error message “One or more blueprints has an unresolved compiler error, are you sure you want to Play in Editor? MyCharacter”.
How to fix this?; because I don’t want to have to restart a whole new “Project”. Any quick fix approach will be appreciated.
ctrl + z 
What do you mean by Default Player? The player mesh or something else in Character BP?
I am talking about when you go to “content browser” tab > Blueprint folder > Double click “MyCharacter” > How to go back to “Default class setup” CharacterMovement?.
This is not a typical “undo” action"Ctl + z; NO!. See screen shot below. I have done a lot of work to start a fresh project and re-do all the assets. There must be a way to
recover from accidents like this. I appreciate any help from anyone.
I am talking about when you go to “content browser” tab > Blueprint folder > Double click “MyCharacter” > How to go back to “Default class setup” CharacterMovement?.
This is not a typical “undo” action"Ctl + z; NO!. See screen shot below. I have done a lot of work to start a fresh project and re-do all the assets. There must be a way to
recover from accidents like this. I appreciate any help from anyone.
The quick fix for me was “NewProject Directory > Rename Directory > Migrate Assets only”…DONE!. everything back to normal.
I dont understand the problem. :\ You can go to Defaults tab from the right top side of that window where it says Defaults > Components > Graph, and Character Movement is in Components tab.
Glad that you figured it out!
Out of curiosity, what was the error message in the character BP? After taking a second look at the screenshot it looks like you accidentally removed/or forgot to set Anim Blueprint Generated Class in the Animation tab of the mesh but i’m not sure.
@ Jacky:
Thanks for trying to help me resolve the issue not cleared to you or anyone I suppose. From the beginning the error message says: " “One or more blueprints has an unresolved compiler error, are you sure you want to Play in Editor? MyCharacter”. Which means when after you build your level, the “default Player” will not work, no movement. something happened as described (not described clearly) withing the “Component Tab” and appeared not recoverable regardless what I try to do. I asked to help me reset the issue back to default. At any rate I did correct it the old fashion way. Thanks a lot Jacky.
It was strange; I have no idea what actually happened but the only error message was as described, when attempting to compile. The class display window detail was not arranged correctly after the fact; I wasn’t paying attention and attempted to compile thus “One or more blueprints has an unresolved compiler error, are you sure you want to Play in Editor? MyCharacter” (error message). Look at these screens, initially my attempt was to use the “owner see / owner no see” options as shown:
http://imageshack.com/a/img540/1881/ZPk45l.png
http://imageshack.com/a/img905/4218/0OjqIf.png
http://imageshack.com/a/img540/1830/Gi97bf.png
I didn’t really understand what happened let alone explain correctly…sorry about that and thanks again. The key is to pay attention but every now and then we get distracted here and there.
Edited one of the screen short:
http://imageshack.com/a/img674/2639/Vib3Xo.png
That rendering option you enabled shouldnt have broken anything, and HeroFFP_AnimBlueprint is selected by default for anim BP generated class as far as i know, but anyway. Let us know if this kind of thing happens again and we can have another look at it to find out what’s wrong. 
Thanks Jacky for your help. For the first time when the compile error pops up; never experience anything like it. My first reaction was to go check “Blueprint folder” and compare with another working “Project Folder”; right away I knew something happened because the “Blueprint folders” of both "Project Folders"looks different. LOL!, I am sitting there wondering what’s going on?;why now?;what did I just did and when?.. it was funny, but I wasn’t laughing because the assets exported from Max took some time including laying out the level in UE 4.3. First intelligent thought is always 99.99% correct, in my case to do a fresh “Project” > move your assets > case CLOSED!. I am sure there are other approaches to fix the issue but I took the easiest…also learn a lesson to pay attention.