Using if else statements correctly

• Are you sure that you need a Boolean? Considering how your code looks, currentPage and testDataGenerated cannot be null (if they would be then they would throw a NullPointerException. Use boolean instead which cannot be set to null
• Try to avoid throwing Exception, create or use a subclass of Exception instead.
• Speaking of "make the code read easier", there is no need to use CAPS LOCK FOR THE EXCEPTION MESSAGES. (Sorry, just had to show you what I mean).

• Use spacing more consistently:

  if (testDataGenerated) {
  

  is better than

  if(currentPage){
  

  Just like } else { is better than }else{

The other answers have provide some good suggestions about the code formatting and styling, so here's mine on the logic.

The way I see it, you only need to call verifyEventDetailFull() when the test data is generated and currentPage is true (I'm not quite sure why the title containing a certain value is 'current page', but that's beyond my point). Otherwise, you 'handle the error' by saying that 'Page synchronize failed' if the test data is generated but currentPage is false, or say 'Test data is not generated' if that is indeed the case.

Given some slight, and in my humble opinion reasonable, assumptions based on the cases I have described above, I have an implementation for the handle error part:

private void handleError(final String testCaseName, final String errorDescription) {
    WriteTo.testgoal(testCaseName, TestgoalState.NOK, errorDescription);
    throw new Exception(errorDescription);
}

I think it's fair enough to use one errorDescription for printing some output and using it for the Exception message. I will now present the full suggestion:

public void synchronizePageAndExcecuteVerifyNode() throws Exception {
    final String testCaseName = this.getClass().getSimpleName();
    WriteTo.testgoal(testCaseName, TestgoalState.nvt, "");
    boolean isTestDataGenerated = eventTestData.eventDetailMultipleDays;
    if (isTestDataGenerated && driver.getTitle().contains(Value.TITLE_EVENT_MULTIPLE_DAYS)) {
        verifyEventDetailFull();
    } else {
        handleError(testCaseName, isTestDataGenerated ? "Page synchronize failed" : "Test data is not generated");
    }
}

private void handleError(final String testCaseName, final String errorDescription) {
    WriteTo.testgoal(testCaseName, TestgoalState.NOK, errorDescription);
    throw new Exception(errorDescription);
}

The only boolean value I need to store first is isTestDataGenerated. It is a good naming convention to begin boolean variables with is. Inside the else part, isTestDataGenerated allows us to switch between the correct error description. As mentioned above, we will only encounter the 'Page synchronize failed' case when the if condition holds true for isTestDataGenerated but false for 'current page'. Or you can simply read it as there is no test data generated, hence that error description in the false clause of the conditional operator.

Names of variables should be chosen well. If you name a variable currentPage, I would assume that it contains a page number (1, 2, 3, 4, etc). If you want a boolean variable that is true if we are on the current page, you could call it isCurrentPage. If you want a boolean variable that is true if synchronization to the current page succeeded (I have no idea what that means in the context, but that's what you seem to be checking), call it isSynchronizedToCurrentPage.

Especially when you change currentPage == true to currentPage, the first one indicates that currentPage is some kind of boolean. Reading if (currentPage) I only think "What???".

I would write like this to improve readability :

if (false == testDataGenerated) {
     WriteTo.testgoal(nameTestcase, TestgoalState.NOK,
            "testdata is not generated");
     throw new Exception("NO TESTDATA GENERATED");
}

if(false == currentPage){
    WriteTo.testgoal(nameTestcase, TestgoalState.NOK,
            "Page synchronize failed");
    throw new Exception("PAGE SYNCHRONIZE FAILED");
}

this.verifyEventDetailFull();