android - R cannot be resolved to a variable, when clean build is done -

i have searched many questions cant seem solution problem. issue came after updated using download manager while eclipse running.

the problem: whenever clean build , "r cannot resolved variable" issue comes. r not present in gen folder. if comment places r used, r.java gets generated, uncomment code containing r.id.. , things run , come again if clean build triggered.

if build normally, changes not getting reflected.

how issue came:

1. download manager - > update.

2. intall 16 packages button - didnt much, because peer connection refused issue came.

3. delete 1 package option. used option twice , deleted 2 folders whise names dont remember.

after projects had thousands of compilation errors. tools folder not present. added unzipping it.

now whenever clean build , "r cannot resolved variable". r not present in gen folder.

if comment places r used, issue gone, uncomment code , things run , come again if clean build triggered.

solutions tried:

1. no issue in of xml's because generates if r not used

2. project -> build project

3. build automatically
4. project -> add support

it seems tool not running properly. earlier, whenever project-> run as->, r generated. apk not present error comes.

update:: project -> run -> error "androidmanifest.xml missing" if open manifest double click, error comes:

parsesdkcontent failed not initialize class android.graphics.typeface  parsesdkcontent failed java.lang.exceptionininitializererror 

have deleted home/.android folder , still error coming. original r error still coming.

update2: 1. issue android manifest error goes clean build. 2. error came, included ..\appcompat_v7 in android library 3. there 2 android-suppport-v4.jar. manually deleted 1 of them. 4. changes not getting reflected on build. , on clean build, r issue comes.

happens me time. try doing rebuild project , clean project. should work.

more solutions @ "r cannot resolved variable"?