Stuck while designing Framework due to error: Module 23

Hello,

While designing framework i am stuch due to some error while running my test.

I was able to execute DummyTestB.java, but then I hit the clean button under "Project" tab in Eclipse. Since then I am getting the below error.

I tried most to fthe solution which I could understand after searching in Google. But could not resolve the issue. 

Please help.

[RemoteTestNG] detected TestNG version 6.14.3
org.testng.TestNGException:
Cannot find class in classpath: com.qtpselenium.core.ddf.testcases.DummyTestB
at org.testng.xml.XmlClass.loadClass(XmlClass.java:77)
at org.testng.xml.XmlClass.init(XmlClass.java:69)
at org.testng.xml.XmlClass.<init>(XmlClass.java:55)
at org.testng.xml.TestNGContentHandler.startElement(TestNGContentHandler.java:575)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.startElement(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.AbstractXMLDocumentParser.emptyElement(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.dtd.XMLDTDValidator.emptyElement(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl.parse(Unknown Source)
at javax.xml.parsers.SAXParser.parse(Unknown Source)
at org.testng.xml.XMLParser.parse(XMLParser.java:38)
at org.testng.xml.SuiteXmlParser.parse(SuiteXmlParser.java:16)
at org.testng.xml.SuiteXmlParser.parse(SuiteXmlParser.java:9)
at org.testng.xml.Parser.parse(Parser.java:152)
at org.testng.xml.Parser.parse(Parser.java:233)
at org.testng.TestNG.parseSuite(TestNG.java:295)
at org.testng.TestNG.initializeSuitesAndJarFile(TestNG.java:348)
at org.testng.TestNG.initializeEverything(TestNG.java:995)
at org.testng.remote.support.RemoteTestNG6_12.initialize(RemoteTestNG6_12.java:22)
at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:97)
at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:251)
at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:77)