I'd delete the index folder and simply let lucene create it. If you manually created those segment files, don't do that... also, if those are the only two files, the write.lock is missing actually.
Just to give you a running example which should work. If you create an empty console project and paste this into the main:
using (Directory directory = FSDirectory.Open("LuceneIndex"))
using (Analyzer analyzer = new StandardAnalyzer(Lucene.Net.Util.Version.LUCENE_30))
using (IndexWriter writer = new IndexWriter(directory, analyzer, IndexWriter.MaxFieldLength.UNLIMITED))
using (IndexReader reader = writer.GetReader())
{
writer.DeleteAll();
var doc = new Lucene.Net.Documents.Document();
doc.Add(new Lucene.Net.Documents.Field("ID", "1", Lucene.Net.Documents.Field.Store.YES, Lucene.Net.Documents.Field.Index.NOT_ANALYZED, Lucene.Net.Documents.Field.TermVector.NO));
doc.Add(new Lucene.Net.Documents.Field("txt", "text", Lucene.Net.Documents.Field.Store.YES, Lucene.Net.Documents.Field.Index.NOT_ANALYZED, Lucene.Net.Documents.Field.TermVector.NO));
writer.AddDocument(doc);
writer.Optimize();
writer.Flush(true, true, true);
Query query = new TermQuery(new Term("txt", "text"));
//Setup searcher
IndexSearcher searcher = new IndexSearcher(directory);
//Do the search
TopDocs hits = searcher.Search(query, 10);
}
It should create a folder "LuceneIndex" under bin/Debug when running in debug mode, adds one document and should find it at the end.
Maybe that helps you get started...